Clamshttp://www.advancedaquarist.com
Below is a listing of all of our articles about clams (husbandry, biology, etc) sorted by date with the newest at the top of the list.
daily12009-05-02T07:30:56Z

On the Giant Clams Tridacna mbalavuana and T. squamosinahttp://www.advancedaquarist.com/2015/3/inverts
Reefkeepers all know the giant clams Tridacna crocea, T. maxima, T. squamosa, T. deresa, and T. gigas. James W. Fatherree introduces two recently described species of tridacnids, one of which is now making its way into the hobby.Click through to see the images.

At the time I wrote Giant Clams in the Sea and the Aquarium (2006), Tridacnacrocea, T. maxima, T. squamosa, T. derasa, T. gigas, Hippopushippopus, and H. porcellanus had been imported for the US reef aquarium hobby. It's time for some updating though, as another species, T. mbalavuana (tevoroa) has now been imported here, and three new species have been described. Of these three, T. squamosina (costata) was the first new one, so I'll give you some information on T. mbalavuana and this species, and cover the other new species in a follow-up article.

Tridacnambalavuana:

While doing surveys of giant clam populations in Fiji in 1985, a few unusual giant clams were found, which got the attention of researchers. The clams were similar to T. derasa, but distinguishable, and after more were collected and studied it was suggested that they might represent a new species. Of course, the locals had already noticed this clam and had named it the devil clam, which is tevoro in Fijian. So, at first it was just called the tevoro clam, and subsequently named Tridacnatevoroa.1,2,3 However, it was later found that this clam had been previously described and named T. mbalavuana in 1934, albeit based only on shells/fossil specimens.4 So, T. tevoroa became a junior synonym of T. mbalavuana.

Further searching eventually led to the discovery of this clam in various areas in the eastern Lau Islands of Fiji and the northern Vava'u and Ha'apai islands of Tonga.3 However, there have apparently been some unverified reports of it living on the outer fringes of the Great Barrier Reef, too.5 So, its known range may be greatly extended in the future if these reports can be verified. If not, then this species has a very small range relative to most other species, and it's relatively rare within its range, as well. In fact, only one was found for every fifty T. derasa around Vatoa, Fiji.1

It's also important to note that this species typically lives in deeper waters than the rest, and holds the depth of occurrence record. Most are found at depths of 20 to 30m, but the deepest-living one reported in the literature was found at 33m (almost 110 feet).3,6 Conversely, all other species of giant clam are found in significantly shallower water, with T. derasa being in second place at 25m.7

Approximate maximum depth of occurrence of T. mbalavuana vs several other tridacnid species.

As far as looks go, the shell is grayish-white, and often bears unusual red patches/bands near the bottom. H. hippopus also bears red markings on its shell, but these are often obscured by the growth of coralline algae, sponge, etc. on the shells of both species.

The shells of H. hippopus also bear red markings, which are especially prominent on smaller specimens.

The shell also typically has 6 to 7 low and wide folds, which are often almost non-existent. Some do have stronger, more convex folds though, and many look very much like the shell of T. derasa. The upper margin of the shell typically has 5 rounded projections on each half, which undulate slightly, and the upper edge is also very sharp. When small in size, the shell also bears petal-like scutes, but these are apparently worn away with age and larger specimens lack them. It lacks a significant byssal opening on its underside, too. The only other thing to note here is that this species is also a big one. In fact, the record length is 55cm (almost 22 inches).3

Typical shell form of T. mbalavuana. Illustration by Laura Hamilton.

Note that the shell of T. mbalavuana can look very similar to those of some T. derasa. Two such T. derasa pictured here, from the Great Barrier Reef.

The fleshy upper mantle tissue comes in a variety of looks. It's often rather dull gray to brownish-gray without colorful or fancy markings, but some are quite attractive, as you can see below. There are three things that are particularly unusual about its mantle, though. It always has a rugose texture, being very knobby/lumpy looking, and it extends very little past the edge of the shell, or not all. Instead of extending it further, the shell gapes open widely and thus exposes a relatively large amount of the mantle anyway.

Two other giant clams, H. hippopus and H. porcellanus, don't extend their mantle past the edge of the shell either, but the rest of the giant clams can and typically do. The mantle also lacks eyes, like H. hippopus and H. porcellanus, while all the other species have them. Interesting, indeed. Lastly, its inhalent siphon, which is the large opening in the mantle, is always ringed by prominent tentacles, which are usually white.3

When it comes to this species and the reef aquarium hobby, as I said above, there has been at least one specimen imported into the US . In February of 2015, Ecological Reef Farms Tonga collected the specimen on the above right and shipped it to a dealer here. Apparently it has an expected retail price tag of $2,000. 8 That's a lot of money for a clam, of course, but I've seen a large blue T. squamosa sell for more than twice that.

This species was also successfully aquacultured at the Tonga Fisheries hatchery in the early 1990's, although it was problematic and not many clams were produced.9 Still, with a price (and profit) like that, and a proven ability to farm them, regardless of problems, I think there's a good chance that more will become available in the future. Considering their paucity on the reefs, and relatively small geographic range, I certainly do not think any significant quantities of them will be collected from the wild, though.

In the event that more are imported, I'll offer some care advice. Considering that this species is typically found in relatively deep water, it is important to give any specimen time to acclimate to intense reef aquarium lighting.

The mantles of giant clams contain structures called iridophores that are made of small groups of cells called iridocytes, which contain stacks of tiny reflective platelets. These can serve multiple functions, but one of them is to help block damaging ultraviolet light. Mycosporine-like amino acids ( MAAs) are also found in the mantle and serve the same purpose, along with some non-photosynthetic pigments.

There is little need to produce these when living at depth, and it has been found that T. mbalavuana has few such iridocytes.3 Thus, it can be rather intolerant of strong illumination. In fact, several specimens died when collected and moved into much shallower waters during initial collections, and was reported to have shown "great sensitivity to sunlight" when moved to the surface.1 Fortunately, more specimens were collected and kept in protective cages at a greater depth of approximately 14m for study and breeding activities.3

Still, in the case with other giant clams, specimens from dimmer waters can typically be slowly acclimated to brighter light over a period of a few weeks, giving them time to produce various materials for dealing with the increase in illumination/UV. Of course, it remains to be seen if this can be accomplished with this species, though. I hope whoever buys/bought the one from Tonga reads this, or has already done their homework!

Tridacnasquamosina:

In 2005, a doctoral student described a unique giant clam found only in the Gulf of Aqaba, which is one of the little fingers at the northern end of the Red Sea. It's appearance was similar to T. maxima and T. squamosa, which are also found in the Gulf of Aqaba and Red Sea proper, but not the same as either. Genetic testing and its reproductive timing, which is not the same as the others, verified that it was different, too.10 It was subsequently named Tridacnacostata, and further searching eventually led to the discovery of this clam in other parts of the Gulf of Aqaba, and off the Egyptian coast in the northern part of the Red Sea proper.11

However, as was the case above, it turns out that this species had already been discovered and named many years earlier. During an exploratory expedition in late 1800's, several specimens of the same clam had been collected in the Gulf of Aqaba and one from the Southern Red Sea off Yemen . These were named Tridacnaelongata var. squamosina.12

The specimens had been in the collections of the Natural History Museum in Vienna, Austria , and were re-evaluated just a few years ago. This analysis indicated that the specimens were indeed the same clam as the ones that had been named T. costata. So, after some taxonomic re-working, T. costata became a junior synonym of T. squamosina.13

The geographic range of the species (at least in the recent past) was then known to cover the Gulf of Aqaba and much of the Red Sea proper at that point, as one specimen had been collected much further south, off Yemen. However, it is now known that its range extends well down the west coast of Africa in the Indian Ocean, and is abundant around the Bazaruto Archipelago off the coast of Mozambique.14 This is almost as far south as the southern end of Madagascar. Whether its range extends even further south, and how far it extends to the east, is unknown at this time, though.

Approximate geographic range of T. squamosina.

While it's now known to be abundant in some areas in the Indian Ocean, it is indeed a rarity in the Red Sea. Surveys indicated that it made up less than 1% of current giant clams stocks there, being found at a ratio of approximately one T. squamosina to every 167 T. maxima and T. squamosa.11 Thus, it was initially suggested that it should be considered "critically endangered" by the International Union for Conservation of Nature. It's interesting to note that, to the contrary, over 80% of fossil tridacnid shells found in the same region are T. squamosina, leading to the idea that this species has been heavily overfished going back as far as the early human occupation of the area roughly 100,000 years ago.11

With the history covered, let's get to appearances. The shell is white, is elongated, and has 5 to 7 deep folds in it, with relatively large, rather pointed tooth-like projections emerging from the upper part of each half. The two halves do not close tightly when pulled together, and there are significant gaps between the tooth-like projections when it is closed as much as it can be. The shell also bears numerous shelf-like scutes, which tend to be well-spaced closer to the bottom of the shell and relatively crowded on the upper part. There's a moderately-sized byssal opening in the bottom of the shell, as well. Thus, it does look similar to, but obviously not identical to, typical shells of T. maxima. Lastly, it also has the same maximum length as T. maxima, at 40cm (almost 16 inches).15,16

Typical shell form of T. squamosina. Used with permission, courtesy of Merlin Charon.

As is common for giant clams, the mantle tissue is quite variable in appearance, and bears a wide range of colors and patterns. It's also papillose, meaning it's covered with little knob-like protrusions. These structures, which are properly called papillae, cover the mantle and are more pronounced and numerous on larger specimens, while the mantles of T. maxima and T. squamosa tend to be relatively smooth. However, some T. maxima and T. squamosa, do bear papillae, although they are fewer in number. The inhalent siphon is ringed with tentacles, like T. maxima and T. squamosa, as well.

Three specimens of T. squamosina. Used with permission, courtesy of Mrutzek Meeresaquaristik (L & M), and Nicole Helgason (R).

Note that some T. maxima shells (L & M) look similar to those of T. squamosina, bearing relatively large "teeth" at the top of the shell. Some T. maxima also bear papillae on their mantle, seen as the small bumps on it (R).

While T. squamosina (L) looks similar to many T. maxima, and is genetically closest to T. maxima, some do look much like some T. squamosa (R). T. squamosina photograph used with permission, courtesy of Julian Sprung.

Another thing of note is that it's typically attached to the substrate, and is found only in relatively shallow water.10 Those found off the coast of Mozambique were in approximately 2 to 9m of water.14 However, all specimens found in the Gulf of Aqaba and northern Red Sea were living at depths less than 2m.11 If this species does not live any deeper than 9m, then it has the smallest vertical distribution of all clams in the genus Tridacna, with the exception of T. crocea, which typically lives within 6m of the surface.

To finish up on this species, I'll again point out that, to the best of my knowledge, it has not been imported into the US . After communicating with several people in the trade, it apparently has not been aquacultured, either. Thus, it is highly unlikely that any will become available in the near future. However, while searching the internet, I did find a photograph at reeflex.net (http://dk.reeflex.net/tiere/2628_Tridacna_squamosina.htm) of a juvenile in an aquarium with T. squamosa. So, somebody, somewhere has had one in a reef aquarium. This site has several photographs of this species if you want to see more.

More to Come?

While reading up on these two species, I found that researchers had done genetic testing on numerous clams in the Red Sea and in 2006 proposed that there were actually two new species related to T. maxima there, as well as one new species related to T. squamosa.17 So, we may find out that there are others there, too. Likewise, as mentioned above, there are two other new species of giant clam found in the Indian and Pacific Oceans, and have already been offered in the hobby. Again, those will be the subject of another article, though.

]]>No publisherJames W. FatherreePomacanthus Publications, Inc.ClamsAquarium InvertebratesJames W. Fatherree2015-03-25T13:00:00ZPageAquarium Invertebrates: A Look at Some Azooxanthellate Epifaunal Bivalveshttp://www.advancedaquarist.com/2014/1/inverts
James Fatherree explores the biology of non-photosynthetic clams, scallops, and oysters commonly encountered by reefkeepers. While most of these bivalves are not impossible to keep with advances in captive reef nutrition, their surprisingly high dietary requirements make their husbandry difficult.Click through to see the images.

Most reef aquarium keepers know something about the commonly-offered tridacnids, otherwise known as the giant clams. But, there are a few non-tridacnid clams that are also available to us, some that hitchhike into our aquariums on live rock and such, and some that just show up seemingly from nowhere from time to time, too. These include a variety of scallops and oysters, and a few other species, none of which are well-suited for aquarium life primarily due to their demanding dietary needs. So, I want to provide you with some general information about the biology of clams and some specific information about why they can be difficult to keep alive long-term in aquariums. I'll also give you some information about a few types of clam that are commonly seen in reef environments and sometimes for sale.

To start, all clams are bivalves. Each half of a clam's shell is properly called a valve, and the "bi" part is obviously added to it because there are two of them. Like coral skeletons, these valves are composed of calcium carbonate, and are produced by the living tissues of the clam. However, clams are about as distantly related to corals as an animal can be. While corals are members of the Phylum Cnidaria and are relatively simple animals, clams belong to the Phylum Mollusca. This phylum is also home to the snails, cephalopods, and a several other invertebrates that are far more complex than the corals and their kin.

Some of these molluscs swim around all the time while some crawl about. Some of them, such as the infaunal clams, live their lives buried in the substrate, too. However, I'll be sticking to the epifaunal clams, which are the ones that live on the bottom rather than in it, or attach themselves to rocks, macroalgae, or other invertebrates, such as corals, etc. And with that said, I want to get back to complexities for a moment.

Clams don't appear to be very complicated animals while just sitting around on the bottom of the sea or an aquarium. However, they actually have a full set of well-developed specialized organs. They have complex gills, a mouth, stomach, and intestines, a heart, kidneys, ovaries and/or testes, a well-developed (albeit brainless) nervous system, and more. Many of them even have eyes. So, they're far more complicated than they might seem.

Oddly enough, several types of clam have eyes. For example, giant clams may have thousands of very simple lens-less, cup-like eyes covering their fleshy surfaces, as seen on the left.1,2 Many scallops and spiny oysters have surprisingly complex eyes though, which have a lens and two layers of retinal cells, as seen in the other two photos.3

This isn't just trivial information, though. Once you realize that a clam is actually a lot more complex than they appear to be on the outside, it shouldn't be too hard to understand why they have a much higher caloric demand than a much simpler animal like a coral. Clams have a lot going on inside their shells, and it takes a surprising amount of food to keep all of their biological machinery running.

To cover their nutritional needs, the vast majority of clams strain various sorts of plankton from the surrounding waters, making them filter-feeders by definition. Their gills are finely branched structures that take in oxygen and give off carbon dioxide, but they're responsible for the capture of food particles, too. They're covered by numerous, microscopic hair-like structures called cilia, which can move back and forth rhythmically to create a current of water that flows over the gills for gas exchange. And, by creating such currents, they also draw in food particles along with the water. As these waterborne particles pass over the gills, many of them stick to their surfaces and are then moved along by cilia into grooves that ultimately direct the particles to a clam's mouth. Various types of particles are also sorted out to some degree along the way to the mouth, and most of the indigestible/unsuitable stuff is discarded. As far as the digestible material goes, many clams can actually use a variety of phytoplankton, zooplankton, and bacteria, but can also make use of some detritus, too. However, for the most part they rely on phytoplankton, specifically.4,5,6,7,8,9

Here you can see a jewel box clam (Chama macerophylla), a species often found on aquacultured live rock from Florida. This one has opened its valves a bit and has extended its tube-like siphons, which are the openings where water is moved into the clam and over its gills, and then back out minus any captured food particles. Water is taken in through the inhalent siphon in the background and leaves through the exhalent siphon in the foreground.

Tridacnid clams are a bit different than the rest though, as they can cover their nutritional needs in more than one way. While they can and often do filter-feed, they also contain large complements of live zooxanthellae in their extendable soft tissues, which are the same single-celled algae that corals utilize. This is why tridacnids are known as zooxanthellate clams, while the rest are azooxanthellate.

As long as a tridacnid clam gets plenty of light, these algae being maintained within its body can make more food then they need for themselves and can donate the excess to the clam host. So, a tridacnid clam doesn't have to rely on filter-feeding when kept under optimal conditions.10 However, azooxanthellate clams aren't so lucky, as they depend entirely on what they can strain from the water with their gills. That might not sound like too big of a problem, except that the plankton they need is typically in very short supply in aquariums. In fact, there may be essentially none present, even in a well-stocked and established reef aquarium. That means if you don't provide am azooxanthellate clam with a steady supply of food yourself, it is very likely to slowly starve to death. And that's exactly what usually happens.

Arc clams (Arca spp.) like these are also found on aquacultured live rock at times. I cannot identify the two small ones on the left to the species level, but the one on the right is the common turkey wing clam, A. zebra, encrusted with coralline algae.

Of course, there are several types of preserved and live phytoplankton products available these days, which can be used to feed a clam. But, as I said, clams have a surprising demand for food. So, even if you try using such a product, you'd need to give a clam a steady supply in order to keep it healthy. I've tried this myself over the years with a few different types of clams and a few different products, and all I can say is that even when using the best stuff on a daily basis, the clams still ended up dead (with a scant few exceptions that I'll get to momentarily). This can take as little as a few weeks or as long as a few months, but the end result is the same - a failure to keep azooxanthellate clams alive long-term. This has been the case in smaller aquariums with few inhabitants and in larger heavily-stocked aquariums, too. I don't recall ever talking to anyone that has done any better either, although I have to assume that someone out there has gotten lucky enough to do so.

Again, note that it can take up to several months for a clam to starve, which can often leave uninformed aquarists frustrated and scratching their heads. The reason why is that an azooxanthellate clam can look absolutely fine for months in an aquarium and the "suddenly" die for no apparent reason. But the fact is, the clam was probably slowly starving all along.

With all that said, now I want to go into a little more detail about one particular type of clam, and also say a bit about some exceptions that I've seen. Dr. Rob Toonen put together an excellent article about flame scallops (Lima spp.)11, which are the most commonly offered azooxanthellate clams out there, and I want to relay some of the info to you. These clams are certainly colorful and cool looking because they have long sensory tentacles that protrude from their shells, but despite their attractiveness, there are actually three reasons to resist buying one.

Flame scallops (Lima spp.) are a commonly offered type of clam, but they shouldn't be.

First of all, they're very likely to starve over a period of weeks to months. We've been over that though, so I'll move on to the other two reasons. Flame scallops also tend to hide when introduced to aquariums, which ends up being very frustrating. When placed in an aquarium containing live rock, these clams will usually scoot around by rapidly opening and closing their valves until they find some out of sight spot, and will stay there. You might be able to find one after it hides and move it back into view in what looks like a good spot, but it'll very likely end up hiding again. Oftentimes, they'll do this over and over until you give up. So, even though they look neat, chances are you won't get to see much of one once it's in your tank, unless you have a relatively barren aquarium.

Also note that if one sits in one place long enough, it can attach itself to anything solid. Many other sorts of clams can do the same thing, including tridacnids, via the production of byssal threads. These tough proteinaceous strands are produced by a specialized organ (the byssal organ), and they're sort of like spider's silk, as they're produced in a liquid form that hardens quickly and can stick to bits of gravel, rubble, or solid substrates. Thus, they can be used by these byssus-producing clams to stay put, making an attached clam more difficult to move. Oftentimes trying to simply pull a clam away from something it's byssally attached to can also damage the clam's byssal organ and associated tissues, sometimes having serious or even fatal consequences. So, you really shouldn't try pulling one off a rock, etc. if it's firmly attached. However, it is possible to carefully cut the threads at their distal end with a razor if you need to, as the clam can discard any damaged ones and produce more when it becomes re-situated.

Here you can see a number of thin byssal threads produced by these flame scallops as a means of attaching to the substrate. These should be carefully cut if you ever have to move one of these clams, or any other byssus-producing clam that is utilizing them.

Lastly, there's their natural lifespan. It's only five years or so in their natural habitat, and that's from the time they're larvae to the time they die. So, if you happen to find a nice big one, it's very likely to already be a few years old, and getting close to its time to expire. This means that even if you have great water quality, can feed one regularly with an appropriate food, and don't mind it hiding all the time, it's still likely to die within a few months, or maybe a year or two at best. All the more reason to leave them where they belong - in the sea.

What about those exceptions I mentioned? Well, for whatever reason, over the years I've had a few jewel box clams and turkey wing clams (both pictured above) that did very well. I didn't buy them as individual specimens though, as they showed up regularly on live rock from Florida waters. I'm not sure how they stayed alive, but I have to assume that these clams in particular weren't as picky about what they ate and could cover their dietary needs with whatever was found in good supply in my aquariums. I'm assuming they could make good use of detritus/bacteria and relied less on plankton, but that's just speculation on my part. Regardless, these clams often lived for years without any troubles. So, if for some reason you're just dying to try an azooxanthellate clam in your aquarium, I suggest trying small specimens of either of these.

Lastly, I have on one occasion had an infaunal clam seemingly appear out of nowhere. While cleaning the sand bed in my 125 gallon mixed reef aquarium one day, I managed to accidentally find the clam pictured below. I did not add this one to the aquarium though, so I'm not sure how it got there. It was alive, so I put it back where I found it and have never seen it again (although I haven't tried to find it, either). I never add planktonic foods to this aquarium, so again, I'm going to assume that this unidentified clam can make good use of detritus/bacteria. It might be worth noting that the aquarium has a deep sand bed, is heavily stocked, and is run without a skimmer, too. It seems there are always exceptions to general rules.

Much to my surprise, I found this good-size infaunal clam buried in the substrate of one of my aquariums, but I didn't put it there...

And, that's about it. One last time I say, the vast majority of azooxanthellate clams do not survive long term in aquariums, unless perhaps you give them a steady supply of an appropriate food. So, they should be avoided and left in their natural habitat unless you're ready to do whatever it takes to keep them alive.

On the left is a knotty scallop (Lyropecten nodosus), one of the more commonly-seen clams for sale. On the right is a common scallop (probably Chlamys sp.), which is byssally attached to a rock.

These are coral clams (Pedum spongyloideum), which are often called iridescent scallops when brightly colored. These clams spend their lives embedded in various corals, usually Porites spp.

On the left is the Atlantic Wing Oyster, Pteria colymbus, which is commonly found byssally attached to the stalks/branches of gorgonians. This one is covered by living sponge, which is also common for this and many other types of epifaunal clam. On the right is a very small specimen of the same species (I believe) that I collected myself. I tried to keep it in one of my big reef aquariums, where it attached itself to the side of a tridacnid's shell, but it died within a month's time.

Cock's comb oysters, Lopha spp. and Pycnodonta spp., like these show up in stores from time to time. While the specimen on the left appears to be bright orange, they really aren't colorful at all. This one is covered by an orange sponge, and sponges are typically difficult to maintain long-term, too. So, both are likely to starve in an aquarium.

These are rock oysters, probably Saccostrea sp. or Alectryonella sp. Many oysters live on hard substrates upon which they can fuse their shells as they produce new shell material.

These are spiny/thorny oysters, Spondylus spp., which are also commonly-offered azooxanthellate clams.

These are variable spiny oysters, Spondylus varius, which are also typically fused to hard substrates.

]]>No publisherJames W. FatherreePomacanthus Publications, Inc.ClamsAquarium InvertebratesJames W. FatherreeScallopOyster2014-01-08T14:00:00ZPageAquarium Invertebrates: A Look at the Giant Clam Tridacna maximahttp://www.advancedaquarist.com/2012/2/inverts
With their desirability in mind, if you can find a good specimen these clams can be relatively easy to care for in a well-run reef aquarium. However, they do have particular lighting requirements, and are by no means bulletproof when it comes to keeping them long-term. So, this article will cover their basic biology, how to identify them, and how to best care for them in aquaria.Click through to see the images.

There are several species of clam belonging to the family Tridacnidae, which are best known as the tridacnids or giant clams. Of these, one of the most attractive species is Tridacna maxima, which is also one of the most commonly offered species available to hobbyists. I say most attractive because they can come in a wide range of colors, which can be arranged in a variety of unusual patterns, with many specimens being striped, sprinkled, spotted, blotched, marbled, etc. The colors themselves also range from black and white, with essentially everything else in between being seen on some specimen or another. In fact, I'd say it's harder to find a maxima that's unattractive than to find one that is.

Basic Information

To get started, maxima is the most widely distributed species of the tridacnids. They're found in the Red Sea and from East Africa all the way across the Indo-Pacific to Polynesia. They also live as far north as southern Japan, and as far south as the Great Barrier Reef (Rosewater 1965). Maximas can be found in high numbers around many reef areas where waters are relatively shallow and clear, with the majority living at depths less than about 25 feet. Some can be found living as deep as about 50 feet, but their abundance drops off dramatically below about 25 feet, with these deeper-living clams occurring mostly as solitary individuals (Jaubert 1977).

Maxima range

Regardless of their depth of occurrence, essentially all of them are found living on limestone substrates, on top of living corals, or on coral rubble. Supposedly they're occasionally found on sandy bottoms (Pasaribu 1988), but after doing a lot of diving around Japan and Indonesia I have yet to see this. Regardless, on hard bottoms maximas can chemically bore a shallow indentation into the substrate that the bottom of their shells fits into, and they strongly affix themselves in place using a tough structure called a byssus. So, they typically stay in one spot for life, with the bottom third or half of the shell kept out of sight in their burrow. Conversely, on coral rubble bottoms they simply bury themselves amongst the coral chunks and attach to something solid with their byssus if they can. Again, usually only part of the shell rises above the substrate. The odd thing is that they won't do this in aquariums, though. It seems that if they don't start making a burrow while they're relatively tiny, they won't do it at all. So, don't expect a specimen to dig into your live rock. Regardless, they almost always attach to the substrate using their byssus anyway.

Aside from that, the most notable thing to point out here is that, like all the other members of the family, maximas harbor large populations of zooxanthellae. These single-celled photosynthetic algae live in the tissues of a host clam primarily within a specialized system of tubes that permeate the fleshy, colorful, mantle tissue that extends from the top of the shell, and when given enough light, they can make far more food than they need for themselves. The extra food (in the form of carbon and energy-packed glucose) is then given to the clam host, which is the same thing that occurs within most reef-dwelling corals.

Under optimal conditions, these zooxanthellae are constantly multiplying within a tridacnid, and some of these live algal cells can be digested by specialized amoeboid cells within the host, too. So, a host clam can rely on its zooxanthellae for more than just sugar, and is considered to be a "farmer" to some degree since it can consume these surplus zooxanthellae grown inside its body.

In addition, all tridacnids can also absorb a variety of nutrients directly from seawater. Their fleshy mantle is covered by a specialized tissue that can very effectively take in dissolved nutrients like ammonia, nitrate, and phosphates. So, here they have a third means of nutrient acquisition, with one more to go.

The last way they cover their nutritional needs is through filter-feeding. All tridacnids can eat fine particulate matter strained from surrounding waters by their specialized gills, which not only work to exchange carbon dioxide and oxygen, but can also act as sieves that can collect such particles. A tridacnid, like most other clams, pumps water into its body chamber, where it flows over the finely-branched gills and then flows out the other end of the body chamber, minus some particulates. These collected bits are can include phytoplankton, zooplankton, and detritus, meaning they can make use of a broad range of things.

Identification

When it comes to identification, once you know what to look for maxima is usually pretty easy to distinguish from all other tridacnids with the exception of T. crocea. So, I'll go over the basic features used to ID them, and then give you some tips on how to differentiate them from croceas, too.

When it comes to shells, they're almost always grayish-white when clean. However, one of the interesting things about the shells of this species is that sometimes they may be tinted with light yellow or pinkish-orange. Rarely, the shell may also be completely yellow. It's almost always strongly elongated in form, being much longer than it is tall, and some maximas are very thin from side to side while others are quite fat. Deformed shells are not particularly uncommon either, as maximas sometimes live in very crowded groups and/or partially burrowed into coral rock preventing them from producing a normally-shaped shell. Regardless, at its top each half of the shell typically has four or five smoothly-curved and inter-digitating projections that are symmetrical to those on the other, allowing the them to close together tightly. However, there are occasional individuals that have more elongated and even pointed tooth-like projections that don't inter-digitate as smoothly with those on the opposite side.

Some species of tridacnids have petal or shelf-like structures on their shells, which are called scutes, and maxima is one of them. In fact, their shells are typically covered by numerous tightly-spaced but thin scutes, which run in rows from the bottom to the top of the shell. However, when maximas partially burrow into the substrate, many of these scutes are either not formed in the first place, or are broken/eroded away in the process. So, maxima shells oftentimes have no scutes on the bottom portion, while numerous scutes are still present on the rest. Still, there are occasional individuals that have none at all for some reason, while aquacultured specimens that are not permitted to burrow typically retain most or all of their scutes.

Also note that it's possible for a maxima's shell to reach almost 16 inches in length, but that's the largest ever reported (Kinch 2002). Thus, you shouldn't expect any given specimen you purchase to get so big. In fact, McMichael (1974) did a survey of several hundred maximas in the wild and reported that only 3% were larger than 9 inches and the largest specimen found in the whole survey was only 9.8 inches. So, that record holding 16-inch specimen was quite an anomaly.

When it comes to the soft parts, maximas typically extend their zooxanthellae-packed mantle tissue well beyond the upper edges of the shell. In fact, it's typically extended to the point that it completely obscures the shell from view when looking down on one. The mantle can also come in such a wide range of colors and patterns that there really is no standard color, although blue is the most common. As noted, the patterns covering it may also be striped, sprinkled, spotted, blotched, marbled, etc. and quite fancy, which is why various specimens are often called things like teardrop maximas, striped maximas, super maximas, or even ultra maximas, etc.

Still, the only patterns that are relatively consistent in how they look are that of the teardrop and striped varieties. Teardrop maximas may vary significantly in color, but they tend to have the same sort of pattern covering their mantle, being covered in teardrop-shaped splotches, while striped maximas tend to have a dark, solid background color with thin radiating stripes of blue, yellow, or white. Other than that, the mantle has rows of simple, closely-spaced, dark eyes near the outer edge and sometimes has numerous eye-tipped tubercles/protrusions on its upper surface, too. The large mouth-like opening in it (called the inhalent siphon) is also ringed with numerous simple, small tentacles that usually lack anything more than very fine branches.

The dark spots on these maxima's mantles are simple eyes.

A typical teardrop maxima.

A typical striped maxima.

Now, as I said above, maximas are indeed easily confused with croceas because both species have relatively large and often brightly-colored mantles with small tentacles around their inhalent siphons. The vast majority of maximas has elongated shells with lots of scutes, while almost all croceas have shorter, taller shells that lack scutes or only have a few small ones. But, there are exceptions, which lead to this confusion. A typical crocea's shell lacks scutes and is far less elongated than the shell of a typical maxima, but there are individuals of each species that are in between. Croceas can be rather elongated at times, and may actually have a lot of scutes, while some maximas may have rather short shells and lack scutes. So, I'll give you some additional pointers for trying to figure out which is which in case it isn't clear who is who.

Some maximas are not elongated (L), while some croceas are (R). This crocea even has a few rudimentary scutes, which are often larger and more numerous on aquacultured specimens.

First, a maxima's shell usually has larger, much more pronounced waves or folds than that of a crocea, as crocea's shells are typically relatively smooth. A maxima's shell sometimes has very sharply-pointed, almost triangular projections at the shell's upper edge, but crocea's are always more rounded and never sharp. Maximas can reach significantly larger sizes than croceas, as the record-holding crocea was only 6 inches long. So, anything larger than about 5 inches in length is almost certainly a maxima. There is no such thing as a teardrop crocea or a striped crocea. Croceas may have some stripes on them at times, but I've never seen one that had a solid background color with thin radiating stripes on top, or the characteristic droplets of a teardrop. And lastly, the tentacles around the inhalent siphon of a maxima are typically simple and un-branched, while those of a crocea are usually finely branched at their tips.

The tentacles surrounding maxima's inhalent siphon are typically simpler than those of crocea.

So, there is no straightforward single way to always ID both species correctly, but by looking at a combination of these features you can usually figure out just about any of them. I will admit though, over the years I've come across a handful of specimens that have been quite difficult to differentiate. At such times most folks just throw up their hands and declare that a hard-to-ID specimen in a hybrid between the two species, but after doing a lot of searching, reading, and asking clam farmers questions I'm still far from convinced that these two species can/do hybridize. That's a topic for another day, though.

Aquarium Care

When it comes to caring for maximas, water quality requirements are typical for reef aquariums in general. Basically, if you're successfully keeping corals alive and well, then your water quality is good enough for a maxima. On the other hand, if you're having problems maintaining excellent water quality - don't fool with any species of tridacnid.

When it comes to water motion, tridacnids live in reef and near-reef environments, and are regularly exposed to strong currents and wave activity. This is especially so for maximas, which often live right at the crest of a reef where waves break hardest. Thus, they are no strangers to strong, surging and turbulent water motion. However, in aquariums the flow tends to be quite linear and constant, as a pump outlet might blast water in one particular spot day and night at about the same volume per minute, and rarely creates any real surge or turbulence. So, you need to think about this when it comes to the placement of a maxima (or any other tridacnid) in an aquarium.

It's okay to expose maximas to a low velocity surge, or to turbulent flow, but putting them in a position where a pump constantly hits them with a strong, non-stop linear current is not recommended. Basically, any sort of current that causes the mantle to fold upwards too much, or over onto itself all the time is bad, as is any current that makes a specimen chronically retract its mantle. Thus, you can put one anywhere you like with respect to current, as long as it doesn't bring on either of these reactions. I'll also add that while they're almost always found on hard substrates and rubble in the wild, placing them on such is highly recommended, but is not required. Placing a specimen on sand/gravel won't kill them, but they often move around a lot, trying to find something to attach their byssus to. Next is lighting, which not surprisingly is of critical importance.

Maximas live at relatively shallow depths where they receive relatively intense light, so fluorescent lighting will only suffice in shallow tanks, or if a specimen is placed on the rockwork near the water's surface in a deeper tank. I would try fitting as many bulbs into the canopy/fixture as possible at that, and mount the bulbs close to the water, and then place any specimens within a foot of the surface, preferably less. Some specimens may be able to get by at times with less light, or further down in deeper tanks, but I implore you to not take chances. Metal halide or comparable L.E.D. lighting is your best option.

I know that some people have gotten by with less, but when it comes down to it insufficient lighting is certainly one of the most common causes of losses. The problem is that corals are very simple organisms that have no real "guts" to speak of, while tridacnids have all the organs you'd expect to find in a higher animal. They've got stomachs, kidneys, gonads, gills, and even a heart. Thus, they are far more complex than you might think, and they use a lot of calories to keep everything running. So, it's a mistake to think that just because your lighting is bright enough to keep corals healthy and growing that they're necessarily bright enough to keep a maxima alive long-term.

To make matters worse, it can take a tridacnid months to slowly starve to the point of no return. So, everything can look fine for weeks on end, then a specimen may seem to just up and die for no apparent reason when it was really starving the whole time. Every maxima is genetically different at that, and long-term experience has proven that some individuals can get by with less while others need much more, even though they may be the same species and even the same size and color. To add, you cannot give a tridacnid too much light as long as a specimen is given time to adapt to intense lighting, so it's better to err on the bright side than the dim side. For more on this, refer to my article On Lighting for Tridacnid Clams in the March 2011 issue, and for even more than that see my book Giant Clams in the Sea and the Aquarium.

You can't overdo it when it comes to lighting, as many maximas are found in the intertidal zone where they're exposed to tropical sunlight that's as bright as it gets.

Lastly, there's the question of whether or not you need to feed a maxima in an aquarium. As covered, all tridacnids are filter-feeders, yet their zooxanthellae can cover a great deal of their nutritional needs, and they're able to absorb pretty much everything else they need directly from seawater. In fact, if provided with enough light, maximas of any size have no need to filter feed and can thrive in particulate-free water as long as there are enough dissolved nutrients present. Controlled experiments by Fitt & Trench (1981) proved that tridacnids can do without, and I kept them for years before anyone was talking about adding phytoplankton to aquaria, much less sold any in a bottle. You can get all the details in my article Tridacnid Clams (Usually) Don't Need to Be Fed in Aquaria in the July 2010 issue, but I'll give you some basic info on the subject anyway.

When you feed your fishes some amount of the food won't get eaten and becomes detrital particles, which maximas can filter out. Any uneaten food also releases nutrients into the water as it decomposes. Likewise, the food that is eaten by the fishes ends up becoming solid wastes that can also become detritus. However, even more importantly, fishes excrete dissolved substances that can be absorbed by a clam, too. For example, fishes give off dissolved ammonia as a waste product, but tridacnids can absorb it and use it as a source of nitrogen. Thus, when you feed your fishes, you're feeding your tridacnid(s), too.

So, the real question is whether or not there are enough fishes in your aquarium to support one or more tridacnids. While it's unlikely to happen, I suppose it is possible to have too low a fish load (or too high a tridacnid load depending on how you look at it) in an aquarium, which would mean that the amount of fish waste being produced would not be enough to support the needs of the clam(s). So, my advice is to refrain from taking any chances and use a quality phytoplankton product if you have any doubts. I have to say though, I imagine that very, very few hobbyists have problems due to nutrient levels that are too low since for most of us the fight is to prevent them from getting to high.

Anyway, I need to wrap things up, and unfortunately I'll going to end on a bad note. As gorgeous as they may be, most all experienced aquarists agree that maxima is the least hardy of the tridacnids. I've seen and heard of more losses of this single species than all the rest by far, and I think it's usually due to insufficient lighting. They are especially dependent on excellent water quality and intense lighting. So, if you don't have both, don't buy one of these.

I'll also add that despite their attractiveness, availability, and relatively low price, really small specimens are even more likely to pass away. In fact, I experienced so many losses of small maximas back in my selling days that I outright refused to order/sell them after a while, and I've heard the same from many other vendors, too. They didn't tolerate shipping and acclimation to aquarium life very well at all, and it was common for more to die in the first couple of weeks than to live. Stick with larger specimens, as in at least few inches long, and you'll have much better odds of success.

McMichael, D.F. 1974. Growth rate, population size and mantle coloration of the small giant clam Tridacna maxima (Roding), at One Tree Island, Capricorn Group, Queensland. Proceedings of the Second International Coral Reef Symposium 1:241-254.

Rosewater, J. 1965. The family Tridacnidae in the Indo-Pacific. Indo-Pacific Mollusca 1:347-396.

]]>No publisherJames W. Fatherree, M.Sc.Pomacanthus Publications, Inc.M.Sc.ClamsAquarium InvertebratesJames W. Fatherree2012-02-22T16:00:00ZPageAquarium Invertebrates: A Trip to an Indonesian Coral and Clam Farmhttp://www.advancedaquarist.com/2011/9/inverts
A few years ago when I was working on my book about giant clams, I was lucky enough to get a tour of the CV Dinar coral and giant clam aquaculture facility in Indonesia. I'm sure a lot of hobbyists have heard of the "farms" in the Pacific, but I figured I'd give you something of a virtual tour of the place and show you a bit about how things are done there. It was quite interesting to say the least.Click through to see the images.

The CV Dinar aquaculture facility, which is more easily called a farm, is located on the northeast coast of Bali, not too far east of Tulamben. It's also around 6 degrees south of the equator meaning the water's warm and there's plenty of sun year round, which gives rise to wonderful coral reefs. And, needless to say, the diving in spots around the island are absolutely incredible.

The main area of the CV Dinar facility.

Some of the gorgeous Tridacna croceca clams they've grown at the farm.

Diving in many areas can be deceptive though, because you typically get to see the best, healthiest areas, while other locations may be in bad shape. Most everyone has heard of the spectre of coral bleaching that has affected so many reefs around the world, and then there are the added insults of pollution, over-collecting, dynamite fishing, shipwrecks, etc. that have all taken their toll on both corals and giant clams, as well. These are some of the reasons that many businesses are aquaculturing a variety of organisms for the aquarium hobby now, and why other organizations are doing the same for the purpose of restocking natural areas. Farming clams has also helped to satisfy the demand for giant clams as food in Asian countries, too.

Anyway, after contacting the farm, I was picked up by Aspari Rachman, the facility manager, and taken for a full tour of the whole place. It isn't particularly big, but they certainly squeeze a lot of livestock into what they have. There are about 30 large concrete grow-out and holding tanks, and quite a few other concrete and acrylic tanks used for various other purposes, too. They have an on on-site lab, and various other buildings, one of which is used to raise their own phytoplankton used to feed infant clams, and zooxanthellae for them, too.

Here you can see some of the pre-shipping holding tanks.

Many of the concrete growing and holding tanks for the clams.

Here is the room where phytoplankton is produced.

They have a huge water intake system at the shore, which allows them to pump water directly from the sea, after which it's run through a series of baffles that contain progressively smaller gravels and sands that act as filters. This water is then pumped through the tanks, making it easy to maintain high water quality. And, in the case of infant clams, the water is also run through micron filters to remove any sorts of parasites, too. Thus, there is a constant turnover of fresh, clean seawater in the systems, with no other sorts of filtration. There's also no need for additional lighting either, as there's plenty of sunlight for free. In fact, the sun does such a good job that they have shade cloth over all the tanks to cut down the amount of light the inhabitants get, and to help keep leaves and such out of the tanks, too.

The Corals

They were growing several types of stony coral at the farm, primarily being Acropora and Seriatopora, and also had plenty of the soft/leather corals Sarcophyton and Sinularia, as well as a few others. All of these were attached to small pieces of rock (which I'll talk about below), and had started out as frags/cuttings from other larger specimens. All of these corals can easily be cut or broken into pieces, and the pieces will live and grow into new specimens. So, they do the same thing that's regularly done by hobbyists and businesses here, but on a much larger scale, and with one big difference. Once the frags/cuttings are made and are attached to a base, they're put in the sea instead of being kept in a tank for weeks or months.

The farm has numerous metal cages on hand, and the corals are placed in these where they can be kept together and get some protection from wave activity and predators, too. The cages are carried maybe 100 yards out off the beach and placed on the bottom in about 20 feet of water. Then they sit for quite a while, sometimes several months. Of course, when you're not paying for salt, additives, and lighting the amount of time they sit is determined by how fast they grow to the size the farm likes rather than moving them to market as soon as they get big enough for someone to want to buy them - and the farm likes them pretty big.

Once the corals have grown large enough to satisfy the farmers, the cages are pulled and the specimens are placed in holding tanks on land. Then they're bagged up and shipped out.

The cages are placed just offshore in about 20 feet of water. Hundreds of them are right under me in this shot, but I didn't get any photos because the water had been clouded up by a storm that passed through a couple of days earlier.

They like to grow the corals to a good size before bringing them in from the cages for export.

The Clams

The farm also raises all six species of giant clam commonly seen for sale over here, being Tridacna crocea, T. maxima, T. derasa, T. squamosa, T. gigas, and Hippopus hippopus. And, they raise H.porcellanus too, which I was looking forward to finally seeing. These are very difficult to find for sale, and haven't been seen in the U.S. market for many years as best as I know. I bought one about four years ago, and the supplier said it was the first they'd ever seen after being in the clam-selling business for over seven years. Despite having at least a couple hundred mature specimens on hand, they told me that none were sent to the U.S. Anyway, while the corals are relatively easy to deal with, the clams take a lot more work, as they obviously can't be cut up to make more.

They also had lots of blue Tridacna squamosa clams on hand, something not seen very often in the U.S. I was quite surprised when they told me that about 10% of the squammies they raise are blue, meaning they aren't rare at all - just rare in the U.S. market.

They also had dozens of full-size Hippopus porcelanus, which are practically impossible to find by in the U.S.

Giant clams are spawners, meaning when the time comes, individuals can spew out huge numbers of sperm and eggs into the water where some will meet the sperm and eggs of other clams. All of them are hermaphrodites when they are mature, so each can produce both sperm and eggs, too.

Well, on the farm they can be artificially enticed into spawning by injecting them with a small dose of the hormone serotonin. Once the hormone is injected into a clam's gonads, it will begin to spew clouds of sperm at first and then the eggs come after the sperm is depleted. So, in order to keep the clams from self-fertilizing (which makes for bad genetics), a clam is allowed to pump out the sperm and is then moved to another tank where the eggs can be released. Then the sperm can be collected from the water and intentionally mixed with the eggs from another clam. This sort of thing can be done with multiple clams, assuring that they have a good mixing of genetic material, which produces healthier clams.

These are the adult broodstock clams used as the source of sperm and eggs.

After all of this, the eggs start to divide and grow, and soon become swimming larvae. At this stage they still do not have any symbiotic zooxanthellae though, as it's not passed from the parents to the offspring. Coral fragments already contain some, of course, but the clam larvae have to get their own complement of the algae by filtering some from the water.

So, the farmers grow zooxanthellae on site using a method they developed themselves, and add a little to the tanks that the larvae are in. The larvae then eat and hold onto it and allow it to reproduce inside their tissues. Other types of phytoplankton are also added, which the infant clams can also eat and used for food. Oddly enough, no one has figured out how it works, but the clams are able to keep the zooxanthellae alive for themselves, while simultaneously digesting other sorts of algae.

Anyway, the swimming larvae drop to the bottom after a short period of time and begin to undergo a metamorphosis, losing the ability to swim and taking on a new life upon the bottom. The farmers continue to add phytoplankton for two months, and they also begin adding nitrogen-based chemicals, too. Giant clams need a source of nitrogen and can extract it directly from seawater in the form of ammonia and nitrate, but giving them extra amounts can increase their growth rates significantly. So, things like ammonium nitrate (fertilizer) or sodium nitrate can be added to help speed things up.

Then, after sitting and growing in a holding tank, typically for more than a year, the clams are big enough to be placed in cages and put out to sea with the corals. At this time they still may be only an inch or two in length depending on the species, so many have a lot of growing to do before they can be sold as good-sized specimens. Some farms do sell clams while still at such a small size, but CV Dinar doesn't. I didn't ask why, but from what I understand, the small clams suffer significantly higher mortality rates, while bigger clams can handle shipping stresses much better.

Once in the cages, the clams are left in place for as long as three more years. So, you can see that this can be a slow process that takes a lot of patience. The timing of collection is primarily due to the species, I should also add, as some clams like T. gigas and T. derasa can potentially grow many times faster than other clams, like T. crocea.

These Hippopus hippopus clams have spent a long time in the cages, and are now ready for export.

Regardless, the farmers are constantly putting out hundreds of clams at a time, and everything ends up running like a conveyor belt. Small ones go in and big ones come out. The seafloor has plenty of space for cages too, so using them and keeping them in the sea means that there can be thousands of clams out at a time while the facility only needs enough room to hold the juvenile clams and those that are ready for export. Everything in between takes up no space in the tanks.

And Live Rock Too

By the way, the rock they need for the bases is made by hand on site by using local stone and cement, and they make lots of artificial live rock ranging from fist-size up to large mounds a couple of feet tall, too. Basically they just lay out some palm leaves on the ground and pile up the concrete-like mix to the desired size. The cement is allowed time to harden, and then the pieces are put in piles in the sea for several months. So, it becomes fully cured there, and also gets some stuff growing on it. In the end, much of it looks as good as much of the live rock coming from the Pacific and is sold as aquacultured live rock. But, they also hold onto some of it to use in re-stocking efforts.

All of the bases and rock they need is made on site.

Restocking Reefs

Again, many reefs are having problems, and the farm has been directed to help out by the Indonesian government. According to Aspari, they are allowed to operate the farm and export livestock as long as 10% of everything they grow is used to help the local reefs. So, they take some of the larger pieces of rock they produce and mount various corals and clams to them, then place them in areas that have been damaged in various ways. They were also trying to start new reefs in some spots, too. All in all, they're doing a great job and helping the hobby and the reefs.

The staff at the CV Dinar facility was exceptionally nice and very knowledgeable, but I have no experience with them on the exporting and business end. This article is by no means an advertisement for them, and is strictly for education.

Sources for more information on clam farming, which can be found online:

]]>No publisherJames W. Fatherree, M.Sc.Pomacanthus Publications, Inc.ClamsCoralAquarium InvertebratesJames W. FatherreeaquacultureM.Sc.2011-09-07T12:00:00ZPageAquarium Invertebrates: On Lighting for Tridacnid Clamshttp://www.advancedaquarist.com/2011/3/inverts
To summarize, it is impossible to give a single number recommendation when it comes to tridacnids' lighting requirements, even for a particular species. Each clam is genetically different, and some members of a given species will need more light than others.Click through to see the images.

As best as I can tell, for as long as tridacnids have been put in aquariums there has been much debate about how much light is needed to keep them healthy. I've heard all sorts of ideas here and there, and have even seen specific PAR values recommended for each species. However, most of what I've heard is bad advice, which is a result of the general lack of understanding of tridacnid biology. So, I'll try to straighten things out this month, and save the lives of some clams.

A beautiful batch of T. derasa, the least demanding of the tridacnid clams available to hobbyists.

Tridacnids are complicated

To start, one of the biggest problems is the false notion that if various corals can be kept healthy under a given lighting system that tridacnids can be kept healthy under it, too. It's easy enough to see why many people would think this, but tridacnids are not corals.

Corals are very simple animals, and they don't really do too much when you think about it. They just sit there and soak up the sun, they don't move around, and they use very few calories from day to day to stay alive. Tridacnids, on the other hand, are actually very complicated animals with mouths, stomachs, intestines, kidneys, gonads, a beating heart, big gills, etc. They also use millions of tiny cilia to draw water into their bodies non-stop. Yes, they just sit around most of the time, but there's a heck of a lot more going on inside that shell than you might think. So, it takes a lot more calories to keep one alive.

Both can get some of their calories by eating plankton and such, but the vast majority of their needs are covered via the photosynthesis carried out by their complements of zooxanthellae. So, they both require light, and tridacnids generally need a lot more than corals. Therefore, you should never assume that good coral growth would equate to good clam growth under the same lighting. More on this in a minute, though.

Tridacnid species aren't all the same

Next, I'll point out that some tridacnid species can live at greater depths than others, and can survive with less light than others. Tridacna crocea, Hippopus hippopus, and H. porcellanus aren't found at depths greater than about 20 feet, and I don't think I've ever seen a single T. crocea living deeper than about ten. However, T. maxima and T. squamosa can be found at more than twice this depth, living down to around 50 feet, and T. gigas can be found even deeper, at around 65 feet. Then there's T. derasa, which can be found all the way down to around 80 feet, and the deepest-living species, T. tevoroa, which can be found down to a about 110 feet (but isn't offered in the hobby). This could be due to some structural differences between the various species, differences in their metabolism, or they may preferentially carry different strains of zooxanthellae, or all of the above, or something entirely different.

Here's a graph showing each species' maximum reported depth of occurrence in meters.

Regardless, intensity at the surface on a bright day in the tropics is around 2,500 µE/m2/s, but at 3 feet below the surface, depending on water clarity, light intensity is already reduced by about 15%, and by 110 feet it has dropped by about 94%. This means intensity drops to about 2,125 at just 3 feet and all the way down to about 150 by 110 feet, and that's in clear oceanic waters on a clear day. So, the deepest living tridacnid has never been found where intensity is lower than about 150 µE/m2/s, and all the rest live in waters where the intensity is higher.

By comparison, I've taken light readings in a couple of relatively dim reef aquariums lit with fluorescent bulbs and found that there are many stony corals that can live and grow under less light than this. Some examples are (in µE/m2/s):

Coral and Light Measurements

Coral Species

µE/m2/s

Pachyseris rugosa

110

Montipora capitata

110

Montipora spongodes

110

Pocillopora sp.

107

Montipora sp.

100

Monitpora digitata

95

Acropora cervicornis

80

Montastrea sp.

80

Acropora millepora

79

Scolymia sp.

70

Turbinaria peltata

64

Turbinaria reniformis

58

Fungia sp.

54

Euphyllia cristata

52

Trachyphyllia geoffroyi

40

Caulastrea furcata

32

Again, all of these were healthy and growing, so it should be clear that you could have a reef aquarium where the light intensity is less than 150 µE/m2/s and still have lots of growing corals, while not having enough light to keep any species of tridacnid healthy.

Anyway, I can tell you for sure that trying to get a T. crocea to live on the sparse light a T. derasa might receive at 80 feet just isn't going to work. Likewise, T. derasa can't live side by side with T. tevoroa at 110 feet. So, how much light is needed depends a lot on which species of tridacnid is being considered.

Individual tridacnids of each species aren't all the same, either

In addition to these species-level differences, there's also variability between individuals. There are countless subtle genetic differences that can make one clam more fit than another under the same conditions, even if they are the same species. Individuals may be carrying different strains of zooxanthellae, too. So, all of the members of a given species can't necessarily adapt to the same minimum light intensity, either. Sibling clams can grow at different rates and grow to different sizes, etc. under the same environmental conditions due to genetic differences, and I'm certain that some clams have varying abilities to deal with more or less light, too.

Here's a good example of how genetically diverse clams of the same species can be. These three T. croceaclams came from the same parents at the same time and have lived right next to each other since being placed in this outdoor tank. Notice the big one is about twice the size of the small one.

For example, I've seen areas where there are hundreds of T. maxima within a few feet of the surface in an area of sloping reef, but their numbers dropped off drastically within the next 20 feet depth, and almost none were living within the last 20 feet of their maximum reported depth. Actually, I'm pretty sure I've never come across one any deeper than about 35 feet. The same pattern of distribution is generally seen with the other species, too. Many individuals in shallower, brighter waters, with abundance dropping steeply as the depth approaches their reported maximum depth of occurrence.

Still, the salinity and temperature are essentially the same across these depths, and larval clams are at the mercy of waves and currents for several days, which can scatter them all over the place. This means that while the larvae are spread across a reef and nearby waters, the ones that settle in shallow waters are apparently more likely to survive while those that settle into deeper waters are not. So, it would seem that some individuals, for some reason(s), are better able to tolerate lower illumination than others, and go on to survive where others can't. They're the tough ones.

Further discussion and my recommendations

With this in mind, you should be able to see that there's no way to come up with a single number that would be the exact minimum amount of light that a species of clam can live under, because one clam's need for light is not necessarily the same as another clam's, even if they're the same species. Basically, the idea of asking for a specific lighting number would be like asking how many calories a day a Cocker Spaniel needs to survive without knowing its age, size, metabolic rate, etc.

This is very important to remember, as you will always want to provide at least enough light to keep any clam of a given species alive, not the minimum that you think an individual of the species could possibly live under. Of course, there are literally hundreds of bulbs and possible combinations of bulbs that can be used over reef aquariums, and they can get dimmer with age, as well. So, I obviously won't be covering every possibility below, but will give some conservative recommendations based on personal experiences and the advice of numerous other experienced aquarists.

To start, I'll say that all available species of tridacnids can and have been successfully kept under fluorescent lighting systems using high-output bulbs with good reflectors and/or metal halide bulbs. So, it is certainly possible to provide what they need through the use of commonly-offered lighting systems.

What about LEDs? Well, I've seen a lot of new LED fixtures over the last few years, and some of them are bright enough to put your eyes out, while many others aren't very bright at all. So, I can't say much about how well they may work with tridacnids. If you want to try, I suggest using an LED fixture with an intensity that's comparable to a metal halide fixture, and then look for shell growth.

Still, in the case of T. crocea, which is apparently the most light-hungry species of the bunch, fluorescent lighting will only suffice in very shallow tanks, or if a specimen is placed very near the water's surface in a deeper tank. I would highly recommend squeezing as many bulbs into the canopy/fixture as possible at that, and then mount the bulbs so that they are as close to the water as possible, and then place the specimen within a foot of the surface, preferably less. Again, some individuals (the "tough" ones) may be able to get by at times with less light, or further down in deeper tanks, but I implore you to not take chances. So, I have to say that metal halide lighting is really the way to go for this species.

By the way, you can't have too much light, as long as a specimen is given plenty of time to adapt to a possible increase over what it's used to. All species available can be found in very shallow waters around reefs and have been raised on farms in very shallow outdoor tanks (like these T. crocea) without being over-illuminated, and our lights don't come close to the brightness of the tropic sun in three feet of water.

Moving along, H. hippopus and H. porcellanus are the other shallowest-living species, and I say give them as much light as you would give a T. crocea. Again, several high-output fluorescents will probably suffice over small tanks, but metal halide lighting is still preferred, and is required for deeper tanks.

T. maxima can live at over twice the depth that these other three can, and should be able to get by with much less light. So, many individuals can be kept under fluorescent systems, even if they're on the bottom of shallow to medium size tanks, as long as there are plenty of bulbs in use. But, they're far more abundant in shallow waters, and much less so at the deeper end of their range, so I still say you should play it safe and go with metal halides, or at least place specimens closer to the bulbs in medium to large size tanks.

T. squamosa can live at about the same depth as T. maxima, but from what I've seen, they don't drop of in numbers with depth to the degree that the other species do. Thus, they seem to be generally better at living under reduced light than T. maxima is, despite the fact that both of these species have the same reported maximum depth of occurrence. This observation has been backed up by my experiences with them in aquariums too, as they've categorically been more tolerant of lower light/greater depth in tanks. Thus, I think it's safe to say that T. squamosa can typically be kept under fluorescent lighting at the bottom of both small and medium size tanks without worry (again, as long as there are several bulbs with reflectors). But, I still say get metal halides for deeper tanks.

T. gigas, on the other hand, is very uncommon near its maximum reported depth, so I'd treat them the same as T. squamosa, even though they have been found many feet deeper. Fluorescents will do in small to medium size tanks, but metal halides should be used for deeper ones. Note that these are giants though, and it's probably best that you don't bother trying to keep a T. gigas in a relatively small tank anyway. So, I say keep a T. gigas in a big tank with metal halides, unless you're absolutely sure that you'll be getting a bigger tank in the (near) future, or can find your oversized clam a new home somewhere else.

Lastly, there's T. derasa, the deepest living species we can get. T. derasa tends to be especially hardy and while using several fluorescent bulbs and reflectors over small to medium tanks is all that is needed, this is the one species that I say can often be kept under fluorescent lights even if they are on the bottom of deeper aquariums. Not always though, as I had one in my 125 gallon tank for a few years that immediately stopped growing after I switched from three 175w metal halides and two 165 V.H.O. fluorescents to 14 three-foot T-5 bulbs with reflectors (seven bulbs over each half of the tank). Even after a few weeks it still didn't resume its growth, and I had to remove it. So, I still say use metal halides if at all possible, just to be sure.

Hard to believe that despite the continued coral growth, this 14-bulb T-5 fixture wasn't bright enough to keep my T. derasa healthy after it had been fine under metal halides for about three years.

Speaking of growth, watching for it is the key to figuring out if you really have enough lights. If your water quality is up to par, and a clam is free of disease, it should add on new shell material if it's getting enough light. So look for new, white material at the rim of the shell. If there's no growth, then the lights are probably too dim. This is important to remember because tridacnids can take months to slowly starve to death, and everything can look fine right up to that point. If they're slowly starving, they won't be doing any growing, though.

Shell growth is a good indicator of health. If water quality and disease aren't issues, there should be some growth if the lights are bright enough. It's seen as the band, thick or thin, of light material at the shell's rim.

To summarize, it is impossible to give a single number recommendation when it comes to tridacnids' lighting requirements, even for a particular species. Each clam is genetically different, and some members of a given species will need more light than others. There is no way to determine this by looking at them though, so to be safe you need to provide enough light to keep any member of the species alive, and the best way to do this is to use intense metal halide lighting, or a fluorescent lighting system that includes quality reflectors and as many bulbs as will fit over the tank. If you're not sure if your lights are bright enough, always look for shell growth, and take action if there isn't any.

]]>No publisherJames W. FatherreePomacanthus Publications, Inc.ClamsAquarium InvertebratesJames W. FatherreeIntensityLighting2011-03-15T14:00:00ZPageFeature Article: Parasitic Copepods: Enemies of Soft Corals, False Corals, Gorgonians, Anemones, Zoanthids, and Tridacna Clamshttp://www.advancedaquarist.com/2010/4/aafeature
This article concludes our brief and incomplete look at copepods capable of potentially harming our captive animals. However, the series will continue with reports of other parasites, including nudibranchs, sea spiders and other 'creepy-crawlies'.Click through to see the images.

Our examination of parasitic copepods will conclude this month with an examination of those 'bugs' known to infest soft corals, gorgonians and Tridacna clams. Oddly, no reports are known to me of hobbyists observing any of these parasites, and no information has been presented in hobby literature that I am aware of.

Figure 1. Paclabius tumidus, a parasite of Tridacnasquamosa. The female of this species can reach 6mm (1/4") in length!

This brings up a couple of questions: Are these copepods restricted to geographical areas where collection of livestock for aquaria is not practiced? Or are we hobbyists, as a group, in need of honing our powers of observation? The goal of this article is to present copepods known to infest marine invertebrates (other than stony corals) popularly found in our captive reefs. Perhaps lack of documentation of these parasites within aquaria is simply due to their small size (usually, but not always, less than 1 millimeter in length). In addition, these copepods sometimes assume the color of their host, possibly indicating ingestion of host tissues.

A listing of parasites found on (or in) soft corals, anemones, zoanthids, gorgonians, and Tridacna clams is found at the conclusion of this article in Table 1.

I have made every attempt to update the taxonomic status of copepods listed in this article, and, in many cases, the status of the host as well. Often, the original Latin name of the animal is listed in parentheses. Sizes of the copepods are the maxima reported.

Parasites of Tridacna and Hippopus Clams

Figure 2. Tridacna and other clams are sometimes infested with parasitic copepods. Photo by the author.

It should come as little surprise that Tridacna clams can be victims of parasitic copepods. It would seem that any animal not enduring parasitic infestations would be the exception.

Parasites of Gorgonians

I've taken the liberty of including hexacorals Antipathes in this grouping, though it is technically incorrect. Gorgonians include sea fans, sea whips, and others. In any case, gorgonians are potential victims of copepod parasites.

Figure 24. Parategastes conexus, a parasite known only from the soft coral Stereonephthya.

Zamolgus acanthodes

Host: Sinularia arborea

Maximum Reported Size, female: 1.09mm

Maximum Reported Size, male: 0.78mm

Color: Translucent, with a few red globules within the prosome, the eye is red and the egg sacs are opaque

Locality: Madagascar

Order: Poecilostomatoida

Family: Rhynchomolgidae

Reference: Humes and Stock, 1973

Figure 25. Zamolgus acanthodes. Other Zamolgus species are found on the soft coral Cespitularia.

Zamolgus cracens

Host: Cespitularia multipinnata

Locality: Madagascar

Order: Poecilostomatoida

Family: Rhynchomolgidae

Reference: Humes and Dojiri, 1979

Zamolgus tridens

Host: Cespitularia turgida

Locality: Madagascar

Order: Poecilostomatoida

Family: Rhynchomolgidae

Reference: Humes and Stock, 1973

Parasites of Anemones

Anemones are quite popular inhabitants of reef aquaria, if sometimes only to act as a home to anemone fishes. We often think of successful maintenance of anemones as meeting their photosynthetic and nutritional requirements. Is there more we should consider? Can an active copepod infestation harm anemones, either through predation or their acting as vectors of disease?

Aspidomolgus stoichactinus

Host: Stichodactyla gigantea (formerly Stoichactis helianthus)

Order: Poecilostomatoida

Family: Rhynchomolgidae

Locality: Barbados, Puerto Rico, Jamaica and the Bahamas

Reference: Humes and Stock, 1973

Figure 26. Aspidomolgus stoichactinus.

Critomolgus actiniae (formerly Doridicola actiniae)

Hosts: Actinia concentrica, Anemonia sculata, andActinia equina

Order: Poecilostomatoida

Family: Rhynchomolgidae

Locality: England, France, Italy

Reference: Humes and Stock, 1973

Figure 27. Critomolgus actiniae, described exclusively from anemones.

Doridicola antheae

Host: Anemonia sculata

Note: There is some doubt about the taxonomic status of this copepod - further descriptions are needed.

Parasites of Zoanthids

Zoanthids have achieved a cult following among many reef aquarists, and with good reason. Their sometimes intense coloration combined with relative ease of maintenance has made them perennial favorites. However, successful husbandry should consider all relevant factors, including parasites.

Parasites of False Corals (Corallimorpharians)

The grouping of 'false corals' includes genera Discosoma, Rhodactis, and many others. Although limited information is available, we as hobbyists should believe that all false corals species are potential victims of copepod parasites.

Paramolgus politus

Host: Rhodactis rhodostoma

Order: Poecilostomatoida

Family: Rhynchomolgidae

Locality: Madagascar

Reference: Humes and Stock, 1973

Figure 33. Paramolgus politus, dorsal view.

Paramolgus simulans

Host: Rhodactis rhodostoma

Order: Poecilostomatoida

Family: Rhynchomolgidae

Locality: Madagascar

Reference: Humes and Stock, 1973

Conclusions

It should be apparent that many (if not most or even all) marine invertebrates popular in reef aquaria are subject to infestations by parasitic copepods. However, we can only speculate at the amount of harm they actually cause.

As a very rough analogy, we can examine how a common parasite might affect its host. Our example is an insect - a flea. They are an inconvenience to many animals but usually not fatal. However, under different circumstances the flea is a vector of deadly disease. Consider the role of fleas in the transmission of bubonic plague (the Black Death) to humans. Fleas were carriers of bacteria obtained while feeding on the blood of rats, and transmitted this ailment to humans.

Are aquatic copepods capable of transmitting disease among marine invertebrates? Ivanenko and Smurov (1996) raise the interesting possibility that copepods might introduce pathogens to its host. This could perhaps explain why some copepods infestations are relatively harmless, while seemingly mild cases of parasitism cause rapid decline and death of the host. As a footnote, the pathogenic bacteria Vibrio has been found attached to some copepods' exoskeletons (though not specifically 'coral' copepods or any Vibrio species known to infect scleractinians).

Disease issues aside, the potential of harm to the coral host by parasites is likely best considered on a case by case basis. It is difficult to believe a large soft coral existing under conditions of optimal lighting, water motion and nutrition could be significantly harmed by even a severe parasite infestation. On the other hand, non-photosynthetic corals are often nutritionally deprived due to either lack of proper food or poor water motion (or their synergistic effects). In this case it seems quite possible that the coral animal could have difficulty in coping with the amount of energy required for tissue repair and maintenance.

The amount of trauma inflicted by parasitic copepods should be considered. A small amount of damage to the thin layers of tissues covering a small-polyp stony coral (such as Acropora species) could possibly have more of an impact on its health than, say, the amount of damage done to a fleshy soft coral.

With as much information as we have, our understanding of soft coral parasites leaves much to be desired. At present, even the acknowledgement of their existence by hobbyists is extremely rare, much less confirmations of these copepods' presence in aquaria. Do these parasites exist on the external portions of corals, or are they endoparasites inhabiting the polyp guts?

We have little reason to believe that existing treatments and quarantine/pretreatment protocols would not be effective against these 'bugs'. However, this too remains to be proven.

This article concludes our brief and incomplete look at copepods capable of potentially harming our captive animals. However, the series will continue with reports of other parasites, including nudibranchs, sea spiders and other 'creepy-crawlies'.

Acknowledgements

Many thanks to Steve Ruddy of Coral Reef Ecosystems (www.coralreefecosystems.com) and Michael P. Janes of AquaTouch (www.aquatouch.com) for providing photographs for this article.

Stock, J., 1975. On twelve species of the genus Acanthomolgus (Copepoda: Cyclopoida: Lichomolgidae) associated with West Indian octocorals. Bijdragen tat de Dierkunde. 45(2): 237-269

]]>No publisherDana RiddlePomacanthus Publications, Inc.AnemonesClamsCoralDana RiddleFeature ArticleGorgoniansParasitesZoanthids2010-04-15T00:00:00ZPageAquarium Invertebrates: A Look at the Hippopus Clamshttp://www.advancedaquarist.com/2010/3/inverts
While you might never see a porcellanus for sale, there's always the chance you will, and hippopus is easy enough to acquire if you want one. So, keep all of this information in mind and do what it takes to keep them alive and well should you make a purchase.Click through to see the images.

Tridacnids, generally called giant clams, are common additions to reef aquariums, most of which belong to the genus Tridacna . However, there are two tridacnids available from time to time, which are not in the same genus with the rest of the bunch. These are Hippopus hippopus and Hippopus porcelanus , the former of which is far more likely to be seen for sale than the latter. Regardless, folks are generally unfamiliar with both of these species, so I'll fill you in.

Hippopus hippopus

Commonly called the hippopus clam, strawberry clam, horse's hoof clam, or bear paw clam, this species is typically found on reef flats, often in grassy areas, living on sandy to slightly muddy bottoms, or on coral fragments and gravels (Barnes 1984 and Govan et al . 1988). Shelley (1988) reported that juveniles are usually lightly byssally attached to the substrate, and that they typically stay attached until they are larger than 14cm. However, Pasaribu (1988) reported that hippopus clams are generally not attached to the substrate. This depends on size and substrate though, with juveniles being attached if possible, and larger clams living unattached and relying more upon their own weight to keep them in place. They also live from the intertidal zone down to about 6m.

Theirnatural range extends from the eastern Indian Ocean from Myanmar eastward across the Pacific Ocean to the Marshall Islands and to Fiji and Tonga, and from as far north as Japan down to the Great Barrier Reef, New Caledonia, and western Australia. However, hippopus has been heavily over-fished and is rare to extinct in many parts of this range (Wells 1997 and Raymakers et al . 2003).

Unlike the Tridacna species, hippopus' mantle, without exception, extends only to the upper margin of the shell. It does not extend laterally out of the shell, as is seen with the Tridacna species. The inhalent siphon, where water is drawn into the body chamber, has no tentacles around its margin, either. However, I have seen small protrusions around the margins of some specimens, and sometimes the siphon's margin can also be somewhat jagged in appearance or rather convoluted/frilly. The exhalent siphon, where water exits, is typically flattened and disc-like, forming a low cone with a circular opening.

The inhalent siphon of H. hippopus lacks fringing tentacles, making it easy to distinguish which species of Hippopus it is.

This species can come in a few colors, but the vast majority has a predominantly yellowish-brown or olive-green mantle with white to cream or golden splotches and/or thin stripes. Others may be more gray in color, but that's about it. They often have considerable areas of rather translucent tissue with lighter or no color, as well.

Here are two nice H. hippopus specimens, one big and one small.

Theshell is usually grayish-white, sometimes with a faint tinge of yellow or orange. However, unlike other tridacnids, it's oftentimes covered by irregularly-shaped red blotches. The shell commonly becomes highly encrusted by other organisms though, so these markings typically aren't visible on larger ones in the wild. It can also be very elongated with respect to the hinge, which is typically a bit more than 1/2 the length of the shell, and may be closer to 2/3 of its length for larger specimens. This allows the shell to gape open very widely. The shells are also strongly inflated, and hippopus is usually quite fat even at small sizes.

The shells can also have a variable number of folds/ribs, often having as many as 13 or 14, in a great range of sizes. However, typically only 5 to 8 of these are more pronounced than the others, and can be relatively convex and rounded, or more straight-angled and box-like. In addition, the larger folds also usually have small riblets on their surfaces, so that one large fold may appear be made of several smaller ones. They also lack the scale-like scutes commonly seen on Tridacna species like T. maxima and T. squamosa , but they're sometimes covered by small semi-tubular structures. These are especially common on smaller clams, and when present they can give the shell something of a prickly appearance.

These tubular structures are found only on the shells of H. hippopus .

The shell halves are symmetrical to each other and can close tightly. They're topped by rather unusual inter-digitating projections though, which are often quite squarish when the clams are young, and become more rounded as the clams grow. There are usually 8 to 12 of these. The byssal opening in the bottom of the shell is usually absent or quite small for juveniles, often being nothing more than a short slot that is closed completely later. This is expected, as hippopus typically maintains only a weak byssal attachment when young, if any at all, and always lives unattached when larger. The area around the byssal opening is rather unique, too, as it's ringed with numerous small, inter-digitating projections/teeth that are absent in Tridacna species.

The byssal opening of both Hippopus species is quite different than those of the Tridacna species, as it bears numerous inter-digitating projections.

They can also get quite large, as Rosewater (1965) reported that hippopus could grow to 40cm in length, with more recent references indicating even larger sizes. For example, Fossa & Nilsen (2002) say the maximum size is 50cm, while Knop (1996) says the record holder is housed at the Marine Science Institute of the University of the Philippines and measures in at 54cm. However, Fossa & Nilsen also reported that 40cm is usually the maximum size, and Smith (1898) wrote about an "unusually large specimen" from the Philippines that was only 34cm in length. So, don't expect one to reach such huge sizes in an aquarium.

Hippopus porcellanus

Commonly called the porcelain clam or China clam, this species is hard to come by in the U.S. A few years ago I bought one from Clams Direct, and the owner told me it was the first one he'd ever seen despite importing clams for over 7 years. I have never seen one offered at a shop, either. However, while visiting the C.V. Dinar coral and clam farm in Indonesia I saw that they had reared quite a few of them, all of which were going to the Japanese aquarium market. For that matter, most all of the best clams they had were going to Japan, too. After living there for two years, I can tell you that they get the best stuff across the board. They pay for it, too…

The C.V. Dinar facility in Indonesia is raising quite a few Hippopus clams. Most of them were H. hippopus , but there were several H. porcelanus , too.

Anyway, like hippopus, porcellanus is typically found on reef flats, often in grassy areas, living on sandy bottoms (Pasaribu 1988 and Delbeek & Sprung 1994). Pasaribu (1988) also reported that porcellanus clams are "generally" not attached to the substrate, and that they also live from the intertidal zone down to only 6m. However, porcellanus has a far smaller natural distribution than hippopus, originally being found only in eastern Indonesia, the southern Philippines, Palau, and Papau New Guinea (Kinch 2002), and later in Malaysia (Raymakers et al . 2003). However, as you might guess, they've also been heavily over-fished and are rare to extinct in parts of this range (Wells 1997 and Raymakers et al . 2003).

Also like hippopus, the mantle of porcellanus, without exception, extends only to the upper margin of the shell. The exhalent siphon is also typically flattened and disc-like, forming a low cone with a circular opening, too. However, unlike hippopus, the inhalent siphon always has large, branching tentacles around it. The majority of these clams have a predominantly yellowish-brown or olive-green mantle with white to cream or golden splotches and/or thin stripes. Some may also be more grayish, though. They also commonly have areas of rather translucent tissue with little or no color.

The inhalent siphon of H. porcelanus is always ringed by tentacles, making it easy to distinguish which species of Hippopus it is.

Here's a large H. porcelanus at the C.V. Dinar facility, and my own specimen, too.

The shell is white when clean, and its appearance is the origin of the common names. "China clam" refers to the look of the shell, not the country it hails from. And, while juveniles have shells that are commonly rather fan-shaped, with the hinge being about 1/2 its length, they do usually become slightly elongated as they get larger. The hinge becomes elongated, sometimes to 1/3 the length of the shell, and the shell also becomes moderately to strongly inflated. Like hippopus, porcellanus is often rather fat.

The shell also typically has 5 to 7 folds, with 5 or 6 being more developed. These are still usually quite low though, and there are no scutes on them, making their shells look similar to that of Tridacna derasa at times. So, despite being closely related species, porcellanus' shells can look quite different from those of hippopus.

The upper margin of each valve is usually topped by 5 or 6 smoothly rounded, inter-digitating projections, which are symmetrical to those on the other valve. This allows them to close themselves up very tightly when they want to. And, like hippopus, porcellanus typically maintains only a weak byssal attachment when possible, and only when young, living unattached when larger. Accordingly, the byssal opening is usually non-existent or very small for juveniles, being only a short slit at best, which becomes completely closed later. The area around their byssal opening also has numerous small, inter-digitating projections/teeth.

As far as size goes, Rosewater was the first to describe this species (1982), but according to Lucas (1988), he only had small species to examine. Lucas had access to larger specimens and reported a maximum size of 40cm.

Aquarium Care

With the basics covered, now we can get to caring for these species in aquaria, starting with water quality. The requirements for keeping these two clams (and the rest of the tridacnids, too) falls right in with what's considered "standard" for reef aquariums in general. Temperatures between 25° and 28°C are optimal, as is a pH of 8.1 to 8.3. Alkalinity should optimally be kept in the range of 9 to 12dKH , and calcium should be maintained at 380 to 450ppm, etc. About the only thing in particular to note is that as these clams grow, they add new shell material to the entire inner surface of the shell, not just the top edge. So, even a slow growing clam can use more calcium than you might expect, and having several in an aquarium can deplete calcium and alkalinity surprisingly quickly.

Other than that, having sufficient lighting is really the key to keeping them healthy. Light falling upon the soft mantle tissue and the symbiotic zooxanthellae harbored inside is the primary means by which all tridacnids get their energy in the wild, and the same goes for life in aquariums, too. So, you absolutely must give them sufficient lighting if you expect to keep them alive.

As mentioned above, both of these clams are not found at depths greater than 6m (about 20 feet). That's quite shallow compared to their Tridacna cousins, with the exception of Tridacna crocea . Crocea also lives from the intertidal zone to about 6m, but the rest of the species can be found significantly further down. For example, the popular T. maxima has been found at depths of 15m, and T. derasa at 25m. Obviously quite a difference.

What this means to hobbyists is that these two clams will need even more light than most other tridacnids in order to thrive. In my experience and based on information taken from the literature, which is covered in detail in Fatherree (2006), they can get by with less light than T. crocea , but their growth rate will be greatly reduced. Thus, even high-output fluorescent lighting will only suffice in relatively shallow tanks, or if a specimen is placed on the rockwork near the water's surface in a deeper tank. I would highly recommend squeezing as many bulbs into a canopy/fixture as possible at that, mounting the bulbs so that they are as close to the water as possible (without causing heat problems).

It's also important to note that there can be a great deal of variability between individuals of any given species of tridacnid. There are genetic differences that can make one clam more fit than another under the same conditions, two individuals may be carrying different strains of zooxanthellae, and so on. So, some specimens may be able to get by at times with less light than others, or further down in deeper tanks, but I implore you to not take chances.

With that said, experience has shown that metal halide lighting is really the way to go, preferably a combination system comprised of metal halide and fluorescent lighting. A standard 175w white to blue-white metal halide bulb should be sufficient for keeping these on the bottom of any small to medium size tanks, as in anything less than 45cm deep (or no deeper than this in a larger tank). But, I'd go ahead and move up to 250w, or even 400w bulbs if a specimen will be any further away from the surface, though.

Next, we get to whether or not you need to feed these in an aquarium. All tridacnids are filter-feeders that ingest a variety of particulates stripped from surrounding waters. However, their zooxanthellae can cover a great deal of their nutritional needs, and they're also able to absorb nutrients directly from seawater. In fact, if provided with enough light, tridacnids of any size can completely forgo the need to filter feed and can thrive in particulate-free water as long as there are enough dissolved nutrients present. I assure you that any claims to the contrary are false.

I dedicated an entire chapter to tridacnid nutrition in Fatherree (2006), which covers how they "work" in great detail, but I'll keep it simple here by saying that, in aquariums, basically everything is taken care of by having good lighting and simply feeding the fishes. Some fish food is left uneaten and becomes detritus, which tridacnids can filter out, and it also releases other nutrients into the water as it decomposes. But, most food is eaten by the fishes, which produce solid wastes that can also become detritus, and also give off dissolved nutrients that can be absorbed by a tridacnid, too. So, when you feed the fishes, you're feeding the clams, as well. For what it's worth, going all the way back to the early 90's, I've kept many tridacnids in well-stocked aquaria topped with metal halide lighting without providing any sort of particulate food whatsoever.

Still, the real question is about stocking levels, i.e. whether or not there are enough fishes in your aquarium/enough fish food going into you aquarium to support one or more clams. It is indeed possible to have too low a fish load (or too high a clam load depending on how you look at it) in a tank, which would mean that the amount of fish waste being produced would not be enough to support the needs of the clam(s). So, my advice is to refrain from taking any chances and use a quality phytoplankton product if you have any doubts. Basically, assuming water quality and lighting are sufficient, you should see shell growth if things are okay, while a lack of growth means they aren't.

You also need to think about water flow, as these two species live in shallow waters on reefs and near-reef environments that are regularly exposed to strong currents and wave activity. To the contrary, water movement in aquariums is typically nothing like that on the reef or nearby, as the flow in most aquariums tends to be quite linear and constant. While it's best to expose them to a low velocity surge and/or to turbulent flow, putting them in a position where a pump just blasts them with a strong, non-stop linear current is not recommended. Basically, any sort of current that causes a specimen to chronically retract its mantle and keep the shell even partially shut won't do. Thus, you can put one anywhere you like with respect to current, as long as it stays open fully.

Next, we get to placing these in the right spot. I think it's best to place any specimen of any sort on the same kind of substrate that you'd find it living on in its natural habitat, but this should be pretty easy since both of these can be found on sand, gravel, and coral rubble in the wild. So, these can be placed essentially anywhere in an aquarium, as long as lighting and current are acceptable.

Okay, with these things that you should do covered, now I'll run through some of the things that you should not do when it comes to the placement of a specimen. As is the case with any species of tridacnid, never place one in a tight crevice between rocks and such, as this may restrict their ability to open fully, and also increases the risk of them falling down into the rockwork if they move around too much. Never stick one in a hole in a rock that might restrict their ability to open fully, either. And, if you do place one in a large enough hole, never let a lot of detritus settle into the hole around the clam. If detritus does accumulate around one, you should blow it out regularly using a turkey baster or powerhead, etc.

Also, if a small specimen has attached itself to a sizeable piece of rock, shell, etc., never try to move the clam and the piece it's attached to by grabbing only the clam. That's a good way to injure the organ it uses to attach to such things, and you should always pick up the clam and the piece together and be very careful when handling the two. Likewise, you should never try to pull one off anything that it's attached to as you can rip the thread-producing byssal organ right out of it. And lastly, don't move a specimen repeatedly over a short period of time. It can be stressful enough trying to adapt to changes in lighting and current when they're moved into an aquarium, and quickly moving them from one place to another to another can be too much at times. Such activities can lead to slowed growth, a greater susceptibility to disease due to stress, or even outright kill them. If you must move one more than once, be sure to give it plenty of time between each move, as in a week
or two at the least.

Well, that's all I've got. While you might never see a porcellanus for sale, there's always the chance you will, and hippopus is easy enough to acquire if you want one. So, keep all of this information in mind and do what it takes to keep them alive and well should you make a purchase.

Wells, S. 1997. Giant Clams: Status, Trade and Mariculture, and the Role of CITES in Management. IUCN - The World Conservation Union. Gland, Switzerland and Cambridge, UK. 77pp.

]]>No publisherJames W. Fatherree, M.Sc.Pomacanthus Publications, Inc.Aquarium InvertebratesClamsHusbandryInvertebrateInvertebratesJames W. FatherreeM.Sc.Hippopus2010-03-15T00:00:00ZPageAquarium Invertebrates: A Look at Giant Clam Spawning in Aquariahttp://www.advancedaquarist.com/2009/8/inverts
Even under the best conditions, only a small percent of the eggs ejected in a spawning event will actually get fertilized, and of those that do, maybe 5% will make it through metamorphosis, or even far fewer than that.Click through to see the images.

From time to time giant (tridacnid) clams will spawn in aquaria, ejecting clouds of sperm, and sometimes eggs, too. Usually this is a sign of excellent health, but it can also be a reaction to heavy stress. Unfortunately, such events won't lead to a tank full of baby clams, and can lead to real trouble in some cases, too. So, I thought I'd explain a bit about how tridacnids reproduce, why they spawn, and why it can be a problem. I'll also give you some advice on what to do if it happens in your tank.

Tridacna crocea

Reproductive Biology

Tridacnids, like other clams, are broadcast spawners. This means that when it's time to reproduce, sexually mature clams will eject clouds of sperm and eggs into the water where they can mix with those of other nearby clams. I say sperm and eggs because fully mature tridacnids are both male and female at the same time, which means they are simultaneous hermaphrodites. Thus, they can make both and spawn both in the same event. They have to be fully mature to spawn both though, as tridacnids develop testes first with quite some time passing before they develop ovaries. So, sub-mature clams may spawn, but release only sperm.

Typically it's a relatively energetic act, as the shell and body contract vigorously making the sex cells spew quite far out of the smaller opening in a clam's fleshy mantle called the exhalent siphon. But, at other times these cells may just slowly sort of ooze out of the siphon and allow currents to do the rest (Alcazar 1988). Even a relatively small species, like Tridacna crocea, may release several million gametes (sex cells) at one time, but a big Tridacna gigas can cough out about half a billion! However, because their sperm have the ability to fertilize their own eggs, successful spawning requires a bit of timing, as self-fertilization is not a good thing.

Usually all of the sperm are released first, over a period of a several minutes, and requires numerous contractions of the body. There are typically only a few sperm coming out at first, but as a spawning event progresses, more and more will be ejected with each contraction, and then the amount will decrease with each contraction as the clam becomes spent. Then, as the sperm runs out, or maybe even quite a few minutes later, the eggs are released in the same manner. Just a few at first, with the numbers then increasing and later decreasing until the clam is spent again (although, again, many times no eggs are released at all). This works a lot better than releasing all of the gametes at the same time, as the sperm can be dispersed and moved away from the parent by currents before the eggs are released.

Here you can see a cloud of sperm being ejected from the exhalent siphon of my own Tridacna derasa. I just happened to be at home and watching the tank when spawning initiated.

When spawning occurs, communicative substances are ejected with the gametes (spawn-inducing pheromones), and these can elicit spawning in other nearby clams, too. So, any tridacnids that are mature enough to produce gametes will start the same routine, releasing their millions of sperm and eggs into the mix with everyone else's. Thus, there's a much higher probability that there will be some genetic mixing within a population of neighboring clams. This may occur year-round near the equator, but it happens more often in the warmest times of the year in higher latitudes. There are numerous recorded exceptions though, as changes in temperature, salinity, lighting, and the tides may all play some part in the timing (Fitt & Trench 1981 and Trinidad-Roa 1988).

Regardless, when fertilization occurs, a new clam is only around 100µm in diameter, and within 12 hours or so the rapidly dividing mass of cells develops into what's called a trochophore larva (Ellis 1998). This is a free-swimming stage, when the miniscule larva can be carried along by currents to new localities. At this time there are rows of tiny hair-like cilia on the outside of the larva, which allows a larva to swim under its own power to some degree, as well.

After another 12 to 36 hours or so, a trochophore larva will pass into the veliger larval stage (Ellis 1998). A velum is a specialized organ that develops at this time, which is also covered by cilia and is used for locomotion, but also for feeding. So, it's during this phase that a larva can start to filter particles from the water. In fact, within the first 2 or 3 days, a clam typically has a well-developed velum, stomach, and intestines, and the shell is already forming, as well. It's fascinating to me that they can go from an egg to all that in a matter of a couple of days.

Timing can start to vary a great deal at this phase and through the rest of development though, as the developmental schedule varies from species to species, and on individual genetics, the condition of the gametes at spawning, and environmental conditions, too. After somewhere between 3 and 10 days, a veliger also develops a foot and is called a pediveliger ("ped" means foot) for some time (Ellis 1998). This foot is a muscular structure that can reach out and help the larva to move around on the bottom, and may also be used to collect food particles for a short time, as well (Reid & King 1988). It looks and acts almost like a sticky little tongue, and once formed, the larva will start to alternate between swimming around and crawling around on the bottom. The digestive system will continue to develop, as well, and so will the shell, while the larva moves about trying to find a suitable place to live. Then, once a spot in chosen, it'll settle down for the next step.

When the timing is right, which can be anywhere from 8 to 29 days after fertilization, the pediveliger will stop moving around and will begin to change into a juvenile clam (Ellis 1998). This change is appropriately called metamorphosis, and involves the atrophy and sloughing away of the velum and the loss of the cilia that were used for locomotion, too. After this, there is no more swimming about, and a post-metamorphic clam, for the most part, looks just like a tiny version of an adult, still being in the neighborhood of only 200µm (1/5 of 1mm) in size.

The gametes don't carry any zooxanthellae from their parents, so a clam must capture its own by filtering them from the water. This can start at the veliger stage at times, even before the specialized system of tubes that hold them in the fleshy mantle has started to develop, and when zooxanthellae are collected so early on, they're simply held in the stomach and stay there until after metamorphosis.

As a post-metamorphic juvenile develops, and the tubular holding system has begun to form, the zooxanthellae can typically be seen moving into the growing mantle within 2 to 7 days (Fitt & Trench 1981). Then they start to reproduce rapidly, while even more are being collected via filter-feeding, and they spread throughout the mantle in just 1 to 3 weeks. From this point on, a juvenile functions essentially the same as a small adult.

The clams that make it through metamorphosis to become juveniles typically grow at relatively slow rates at first. In fact, it may take them several months to make it to just a few millimeters in length. However, at some point their growth rate usually increases and continues at a faster pace until they approach sexual maturity and become adults themselves. Growth during this period, between the early parts of the juvenile phase and the mature phase of life, is also usually fairly linear, although things like changing environmental conditions, predation, disease, etc. can slow things down, of course.

As mentioned above, they don't become completely mature all at once, though. Depending on the species, an individual's genes, and the environmental conditions, a clam may become a fully-functioning male that can eject millions of sperm in as little as a couple of years, but may not become a functioning female for many more years after that (Lucas 1988). For example, Braley (1998) reported that it can take Tridacna gigas 4 to 5 years to become male-mature, and then another 5 to 6 years to become female-mature.

Many clams can become fully mature faster than this though, as Nash et al. (1988) reported that Tridacna gigas can become male-mature at 25 to 35cm, which is likely a year or so faster than Braley's observation of 4 to 5 years. And, Tridacna derasa can become female-mature by that size according to Adams et al. (1988), which is also in the 5-year range. Likewise, Heslinga (1993) said that Hippopus porcellanus could become a female-mature in four years, and Benzie (1993) said Hippopus hippopus could do it in only three. That's quite a difference in schedules.

My artist's rendering of a tridacnid pediveliger larvae. Not much to see other than the valves, the velum (blue), and the foot (green) sticking out. (pediveliger)

Spawning in Aquaria

So, they do spawn in aquaria from time to time, but this can lead to serious trouble in the closed confines on a tank if you don't take immediate action. In fact, if the gametes aren't cleaned up quickly, there's a chance that a spawning event can lead to the death of everything in the tank! So, let's look at some of the things that might cause a clam to spawn (so that you can avoid them), and then what to do if it happens anyway.

First of all, spawning is a natural occurrence, thus healthy and mature tridacnids may spawn in aquariums as a normal part of life. However, they may also spawn if they're mature and are subjected to too much stress. When something goes wrong a clam may respond by ejecting any gametes it's holding, as this may ensure the survival of some of its potential offspring if it should be killed. Remember that tridacnids also give off spawn-inducing pheromones, too. So, if something entices a clam to spawn early, the rest of the clams in the area will likely do the same. In the wild, the gametes and fertilized eggs may be carried away by currents to other areas that have more favorable conditions, and the population's genes would stand a much better chance of survival if things went really bad for the parents.

Natural spawning will occur when a clam becomes ripe with large stores of gametes, but "survival spawning" as I call it, can occur at any time, whether a clam has only a few gametes or a full complement. It also doesn't matter if a clam is only at the male-phase of sexual maturity and can release only sperm, rather than both sperm and eggs, either. It's simply a last-ditch effort to save their genes, so whatever is there will be ejected, whether a clam is really ready to spawn or not.

I managed to make a short movie using a digital camera. Here's part of it, so you can see the strong contractions that typically occur during spawning. Note: everything else looks so still because I momentarily turned off the pumps for better viewing. There were only two clams in this 125 gallon tank, and only the derasa spawned, so didn't bother to remove it until after it released several spurts of sperm. Click the image to watch the movie.

The cues for something like this to occur can be wide-ranging, as essentially anything that over-stresses a clam can bring it on. A rapid change in temperature, up or down, can certainly do it. So can generally poor water quality, rapid changes in salinity, rapid over-illumination, predation or pestering, disease, physical damage, or anything else that's potentially life threatening.

In aquariums in particular, temperature change is likely the most common reason for survival spawning, but it can also happen after doing a really big water change rather than regular smaller changes. This can shock a clam due to some rapid fluctuation in water quality and possibly salinity, and adding too much freshwater at once to replace evaporated water can have the same effect, particularly in relatively small tanks (because it rapidly decreases salinity). Delbeek and Sprung (1994) also reported that adding a lot of new carbon can do it, as can waiting too long to replace old bulbs, both of which can lead to a rapid increase in light.

Of course, if something affects several clams in one tank simultaneously, then they may all spawn as a reaction to the environmental stress. However, if a single clam is suffering from an injury, disease, pestering, etc. it may undergo survival spawning, which can chemically trigger spawning in other clams, even if they aren't stressed. So, if you have more that one clam, having all of them spawn simultaneously doesn't necessarily mean that they are all stressed.

Now you might be thinking that survival spawning is a bad thing, but that a natural spawning in your aquarium by a healthy clam, or several, would be really neat. I remember bragging (to myself) about how great my own reef aquarium was and how healthy my clams were the first time this happened in one of my tanks, as it can certainly make you feel successful. However, I can assure you neither type of spawning is a good thing when it comes to the effects that they can have on a tank's water quality. As I said above, spawning can end up killing everything.

No, the gametes aren't toxic. In fact, they can be a very nutritious food source for many other things in an aquarium. Instead, the problem is that they'll all die in an aquarium and basically rot. They'll do it quickly, at that.

The gametes will start to die in about an hour, if not sooner, and because they all die and begin to decay relatively simultaneously, they can potentially cause oxygen levels in a tank to drop so low that all the fishes and other tank inhabitants may drop dead within a couple of hours. If eggs are released along with sperm and some of them are fertilized, they'll die too, due to the over abundance of sperm. In the wild, the gametes are immediately diluted into millions of gallons of seawater, but this obviously isn't going to happen in an aquarium. The problem is that when too many sperm try to fertilize a single egg, it kills that egg (it's called polyspermy). The precipitous drop in oxygen levels, when the gametes decay can also cause a spike in ammonia and nutrient concentrations, as well. That's bad too, as too much ammonia can also kill everything in an aquarium, and increased nutrient levels invariably lead to outbreaks of unwanted algae. Obviously, there's nothing good about
any of that.

Of course, if something like a single 8cm male-mature Tridacna crocea spawns in a relatively large tank, it may not be a big deal. But, if larger clams spawn, or if a tank is small in size, you must take action immediately. The first thing to do is remove a spawning clam if at all possible. The clam can be temporarily placed into another container with some tank water, where it can release all of its gametes without fouling up the aquarium. If you have more than one clam, this may also prevent any others from joining in if you catch the first one in time.

Keep in mind that a clam may need to stay in the container for quite some time before it is completely spent, so you may need to pour out the water in the container and refill it a couple of times, and you should also add a powerhead pump or an air pump/airstone to keep oxygen levels up if possible. While this is going on, you should also make up a new batch of seawater to replace whatever you remove from the aquarium, too.

If the spawning clam(s) can't be removed, if possible, you can use a length of hose to create a siphon and suck up the gametes as they are being discharged. You can hold one end of the hose near the exhalent siphon of the clam, where the gametes are ejected, and run the other end to a bucket. However, instead of draining the whole tank while waiting for a clam to become spent, you'll need to hold your finger over one end of the hose to stop the flow of water, and only remove it and let the water flow when a pulse of gametes is released.

Likewise, you may be able to use a hose attached to a mechanical filter to suck the gametes up without removing water form the tank. I don't usually use cartridge-type filters on reef aquariums, but if you have one handy you can affix a hose to it and let the filter element collect the gametes. Of course, if you don't have a hose, you can just let such a filter run as it normally would, on the side of the tank or underneath it, too. But, it will take much longer to clear the water if the gametes aren't slurped up as quickly as they are released. Also note that the filter media should be cleaned out thoroughly afterwards, as the gametes will break down in it just as fast as they will in the tank.

Another method, described by Knop (1998), would be to use a pump and hose of some sort to collect the gametes and then direct the water through some form of perforated container filled with cotton or nylon wool. According to Knop, the gametes will stick to these materials due to a static charge, but I've never tried this myself.

Aside from these means of filtering out gametes, you should also do a substantial water change. I would say 25% for sure, and then see how things are looking. This will help to remove some of the remaining gametes, and can also reduce the concentration of ammonia if it has spiked. You should also test the water for ammonia afterwards if you are worried, and change even more water if you feel it is necessary.

Aeration in the tank should be increased in any way possible to keep oxygen levels up, from adding some airstones to positioning any powerheads that you have in such a way that they really make the water's surface roil. Many powerheads have little hose attachments that come with them, which can be used to blow large numbers of bubbles into the water, too.

Once everything is under control, it's also important to stop and think about what might have brought on the spawning event in the first place. If you feel that is was a natural, healthy event, then don't worry. However, if you feel that a clam(s) spawned due to stress, you need to try to determine the source of the stress and take action to correct the situation. Fortunately, if you can get things cleaned up, can figure out the reason a survival spawning event occurred, and then correct the situation, the clams that spawned will still have a good chance of recovering and everything else will be fine.

No Baby Clams

Lastly, I want to point out why you won't end up with a tank full of baby clams after a spawning event. Even under the best conditions, only a small percent of the eggs ejected in a spawning event will actually get fertilized, and of those that do, maybe 5% will make it through metamorphosis, or even far fewer than that. For example, Fitt & Trench (1981) reported that more than 95% of all the veligers in their study that had made it at least 3 days did not make it on through metamorphosis, regardless of the experimental conditions. This is due to microbial attacks for the most part, as the use of various antibiotics has been shown to greatly increase survival (Ellis 1998).

So, mortality can obviously be staggering when they're young, as thousands upon thousands succumb to microbial attacks and other problems. All those sperm, eggs (fertilized or not), veligers, etc. are also subject to being eaten by various filter-feeders and tiny predatory organisms, and then as they grow they may be eaten by crabs, worms, fishes, and myriad other critters, as well. Any sort of mechanical filtration would also strip them out of the water, as can a skimmer, and it's questionable that they could survive a trip through a powerhead or other pump. Polyspermy will ensure that few, if any, eggs would survive long in an aquarium, anyway. So, don't get too excited…

]]>No publisherJames W. Fatherree, M.Sc.Pomacanthus Publications, Inc.Aquarium InvertebratesBreedingClamsJames W. FatherreeM.Sc.aquaculturecaptive breeding2009-08-15T00:00:00ZPageFeature Article: A Look at "Mysterious Clam Deaths"http://www.advancedaquarist.com/2009/3/aafeature1
James gives us an overview of some of the things that can kill tridacnids, most of which aren't so mysterious.Click through to see the images.

Well, I wrote a book about tridacnid clams (Fatherree 2006a) and have been traveling around talking about them at club meetings and conferences for a couple of years now. I generally talk about providing them with sufficient lighting and whether or not they should be feed in aquariums, but I consistently get hit with the same story and questions wherever I go. With great regularity, someone tells me about losing a tridacnid, often one they've had for a while, for no apparent reason. And, of course, they want to know what happened to it. According to many of the stories, such losses often occur when everything else in a tank is fine (even other tridacnids), ruling out any general water quality problems. So, I call these cases "mysterious clam deaths."

With this in mind, I'd like to give you an overview of some of the things that can kill tridacnids, most of which aren't so mysterious. Many tridacnids fall due to stresses incurred from collection and shipping, but this would typically occur shortly after making it home, if they make it to a home. So, I won't spend any time on that. Instead, I want to go over things that, again, could cause a tridacnid to die after it has been in an aquarium for a longer period of time. For now I'll tell you that I get the impression that the majority of mysterious clam deaths are due to microbial or lighting issues, but we'll get to that momentarily.

First, I want to point out that, much to the dismay of clam keepers, in many cases there are no problem-specific symptoms of particular troubles. There are no treatments, or at least no easy treatments for many things, either. Instead, in so many instances, you may not know that anything at all is wrong with a tridacnid until it starts to gape open, and then it's usually too late to do anything to help it - even if there is some way to help it. Gaping simply means that a tridacnid's shell sits open, typically more than normal, but the mantle tissue is rather flaccid and not extended as far as normal (or at all), with the clam typically reacting sluggishly (or not at all) to any sort of stimuli.

This is what advanced gaping looks like. The shell is wide open, but the mantle is flaccid and is not extended.

The shell margin of this gaping T. maxima is also discolored, again indicating that the clam has been in poor health for some time.

This is indeed the number one sign of trouble, but it's also oftentimes the only obvious sign of trouble. Gaping can be brought on by just about anything that has negatively affected a tridacnid's health to the point that it is near death, which could be environmental trouble, such as poor water quality, or disease, such as a bacterial infection of some sort, or any number of other maladies. So, gaping is a sure sign of an impending death, but seeing it probably won't be of much help when it comes to deciding what, if anything, to do. Besides, after being in the hobby for the better part of 20 years, I don't recall a single incidence of a tridacnid recovering, despite any form of treatment, once it has reached a state of health so poor that it begins to gape.

And with that said, here's the list:

Bleaching

Tridacnids carry a complement of zooxanthellae, just as symbiotic corals do, and when conditions are unsuitable they can bleach out, just as symbiotic corals do. Basically, bleaching results from the loss of zooxanthellae and pigments in a tridacnid's mantle tissue causing it to lighten up in color. There are several things that can cause this to occur at some scale or another, but unacceptable increases in light intensity ("light shock") and/or temperature are the main culprits.

This specimen of T. derasa is in the process of bleaching out. The signs are obvious, as a significant portion of the mantle has lost its color.

Tridacnids have several means to protect themselves from over-illumination and can adapt to increased lighting over time. However, if the amount of light, especially UV light, a tridacnid receives increases faster than it can adapt, the result is literally an overload of the photosynthetic process (Osmond 1981 and Asada & Takahashi 1987). Unacceptably high temperatures (and sometimes low) are also problematic and can have the same effect on photosynthetic systems.

However, despite its sometimes lethal effects, bleaching is not a cause of mysterious clam death, as it has obvious effects on the coloration of a clam, which anyone should notice. Patchiness can develop when it starts, and if the condition progresses a tridacnid will turn almost completely white. This often takes days, or even weeks, too. So, you'd definitely see it and it would be obvious that something's wrong. No mysterious deaths.

Predatory and Parasitic Snails

There are several species of snails in the genera Cymatium and Chicoreus that prey on tridacnids, some of which can grow as large as 10cm in length (Govan 1995). Most are smaller than this though, and can enter a tridacnid through the byssal opening, or can puncture the mantle by attacking from the shell margin or elsewhere when the shell is open, and then begin to eat a tridacnid's soft tissues. So, if you happen to spot a suspicious snail on the outside, or especially on the inside, of a tridacnid, you'll need to get rid of it immediately. Algae eating turbo snails, astraeas, conchs, and other well-known non-carnivores are fine, but I'd be wary of anything else. Fortunately, as far as I know these predators are not offered in the hobby, and I don't personally know of anyone that has lost a tridacnid to a predatory snail.

Conversely, a number of parasitic snails belonging to the genera Pyrgiscus, Turbonilla, and Tathrella, do kill tridacnids in aquaria with some regularity. These snails use a trunk-like snout called a proboscis to puncture a tridacnid's mantle near the shell margin and then feed on the victim's body fluids, and if too many attack a tridacnid, it can weaken or even kill it. These pyramidellid snails, better known as pyrams to hobbyists, are well-covered by Cumming (1988) and Boglio & Lucas (1997), but I'll give you the basics.

These are pyram snails, hiding under the bottom of a T. derasa. They're small and light colored, so you really have to look closely for these.

They reach a maximum size of just a few millimeters, are light colored, usually hide under a tridacnid or in the substrate during the day, and are thus very difficult to spot. So, you have to look very carefully for them, usually at night, if you can't remove a tridacnid to inspect it up close. They can also move from one clam to another if they choose, and they can reproduce very rapidly if left alone.

Once mature, these little snails will produce small, gelatinous, egg-filled globs on the shells of tridacnids every few days, which are transparent and particularly hard to spot. And from these globs can spring up to a couple of hundred offspring within just a few days. As if that's not bad enough, the offspring can feed on a clam, become sexually mature, and start to lay egg masses themselves in as little as a few weeks.

Without any natural predators to keep them in check in an aquarium, you can imagine how quickly a clam could succumb to their numbers. So, if pyrams or their egg masses are found on a clam, they must be scrubbed off with a stiff toothbrush immediately, and you should watch carefully for any signs of re-infestation. Of course, these could certainly lead to a mysterious clam death, as the snails and their eggs are hard to spot if you're not looking, and an infested clam will typically look fine until it gets so weak that it begins to gape. Note: You can find much more information about these snails and what to do about them online by taking a look at Fatherree (2006b).

Worms

There are several types of worms that may also pose a threat to the health to tridacnids. One of these is Urastoma cyprinae, better known as the oyster gill-worm, which is a type of turbellarian flatworm. These small worms are sometimes found in the mantle cavity, often on the gills, and in the digestive tract of Tridacna gigas and T. maxima, as reported by Goggin & Cannon (1989). However, they don't seem to have any adverse affects on the health of these clams in the wild. Still, in a closed aquarium system and/or under stressful conditions, I'd imagine they may become problematic. Humphrey et al. (1987) reported that some clams carried an unidentified turbellarian flatworm and the nematode roundworm Syringolaimus, but no specific problems were mentioned. So, yet again, they may not be anything to worry about in the sea, but they may also become a problem in aquariums. And, Newman et al. (1993) reported consistently finding the polyclad flatworm Stylochus matatasi associated with the death of Tridacna gigas in one study of clam mortalities, which, unlike the others, may actually be large enough to see, as they can reach a full size of about 6cm. However, while they may be spotted at times on the mantle, they can also do their damage inside the mantle cavity where you more than likely wouldn't spot them until after a clam is dead and removed. So, again, any of these may have the potential to cause a mysterious clam death, as there no distinctive symptoms will appear until a clam is weakened to the point of gaping.

There are also a number of errant polychaetes, commonly known as bristle worms, which have the potential to kill a clam. A few can get ridiculously large, with a handful of species reaching lengths of one or more meters, and some are indeed carnivorous. However, these relatively large and potentially dangerous species are actually very, very uncommon in aquariums, and they represent only a tiny percent of the hundreds of species of bristle worms that can be found in the seas. To the contrary, the overwhelming majority of species are quite harmless, and are actually beneficial in aquariums, as many are scavengers and/or detritus eaters.

However, there is the remote possibility that you may unintentionally introduce a carnivorous species to your tank, maybe hidden in a piece of live rock, so you should watch out for any worm that is obviously attacking a tridacnid. Likewise, there is at least one species (Oenone fulgida) that can apparently bore a hole through a clam's shell and then chew on its tissues (Delbeek & Sprung 1994), so watch out for anything like that, too. It shouldn't be difficult to spot, as this worm may be only about 2.5mm in diameter, but can reach a length of around 30cm and is bright orange in color.

Still, I personally have never seen any evidence whatsoever of a bristle worm attacking a healthy clam in any way. Yet what I have seen is scavenging worms coming out and feeding on the tissues of a very unhealthy or dead clam. So, if you happen to lose a tridacnid and then discover that there are some bristle worms crawling around inside it, don't assume that the worms were the cause of death. In other words, there's a chance that a mysterious clam death may be brought about by a hungry bristle worm, but it's a slim chance.

Microbial Problems

A tremendous number of bacteria are found in seawater, but they typically aren't a problem for healthy tridacnids. However, if a clam is stressed and its ability to defend itself is reduced, these same bacteria can become deadly. And, to make matters worse, bacterial populations can be much larger in aquariums, as they are closed systems with relatively high nutrient levels. In fact, Fitt et al. (1992) wrote that even small amounts of organic material added to seawater can lead to a 1000-fold increase in bacterial populations within a matter of hours in some situations. Thus, anything from excessive changes in temperature, salinity, lighting, etc., or something like a physical injury (like damage to the byssal organ during a relocation or a nip from a fish, for example) can compromise a clam's immune system and in turn lead to a quick death in an aquarium.

Humphrey et al. (1987) listed off quite a few of these potentially dangerous bacteria, including various species of Vibrio, Acinetobacter, Enterobacter, and Pseudomonas, and Knop (1996) added Xeromonas and Plesoimonas, too. Then there's a rickettsiales-like bacteria, that forms cysts on the gills of Hippopus hippopus, which was reported by Norton et al. (1993a), and an unidentified bacteria found on the gills of Tridacna gigas, reported by Norton et al. (1993b), too. Apparently any of these have the ability to kill a clam, and again, the only symptom of trouble that you might see is gaping, and possibly some necrotic mantle tissue.

Likewise, a protozoan by the name of Perkinsusolseni has been found in the digestive tract of Tridacna crocea, T. maxima, and T. gigas (Goggin & Lester 1987 and Goggin 1996), which can possibly lead to a clam's death. But, as you'd expect by now, there are no diagnostic symptoms that you can identify, and there's no recommended treatment even if you could.

An unidentified protozoan was also found along with Perkinsus in dead and dying specimens of Tridacna maxima, T. gigas, and Hippopus hippopus in some areas of the Great Barrier Reef and reported by Alder & Braley (1988). They were looking for the possible cause(s) of a great number of relatively sudden deaths of many clams when they found these two protozoans, but could not determine if one or both were the actual cause of the deaths. There were no specific symptoms of trouble in this case either, as the only indication that something was wrong was the death of the clams.

Marteilia spp. is a protozoan known to attack the digestive tract of oysters, and Norton et al. (1993c) reported a Marteilia-like protozoan that attacked the kidneys of Tridacna maxima, too. Again, there are no outwards symptoms of trouble, infection can lead to death, and there is no recommended treatment.

Another unidentified protozoan has also been found in the blood of many specimens of Tridacna crocea, as reported by Nakayama et al. (1998). In fact, in one survey they found it present in 77 of 99 clams tested. They didn't report any noteworthy effects, but the things are still there and I would guess they could become a problem in some situations.

And, yet another unidentified protozoan can invade the mantle tissue of Tridacna gigas and consume the zooxanthellae according to Humphrey (1988). However, its effects are poorly understood, too.

Knop (1996) also reported that an unidentified protozoan similar to Perkinsus was reported to attack Tridacna crocea, T. maxima, and T. squamosa. The organism produced small white cysts on the upper and lower surfaces of the mantle and around the byssal opening, and was 100% fatal when left untreated. So, this one actually has signs of trouble that you can see, and Knop gave it the appropriate name "whitespot disease". Unfortunately, it is also apparently very contagious and leads to death in a few weeks to a few months time.

However, there is one disease called "pinched mantle" that can be easily recognized, which is also thought to be caused by yet another unidentified protozoan (Barry Neigut, pers. comm.). This condition can be spotted when the smooth, curving edges of the mantle are pinched and contorted. The clam may look like it is doing its best to stretch out the mantle tissue, but the margins just won't extend fully the way they should. So, this wouldn't be mysterious, either.

This specimen of T. crocea is suffering from a severe case of pinched mantle. The edges of the mantle are curled and literally look pinched.

This T. squamosa is also suffering from pinched mantle. It was healthy until an infected clam was added to the same tank.

A good indicator of good health is the presence of a clean band of new shell material at the shell's margins. It may be bigger or smaller than these depending on a clam's growth rate, but there should always be at least a little new material.

According to Neigut, it affects Tridacna crocea most often, with the other species being more resistant, but not immune. And, it can spread to other clams at times, being nearly 100% fatal, usually within a week or two of the first signs. Pinched mantle can be treated by giving an infected clam a freshwater dip for approximately 30 minutes, and Neigut has had good results with the use of the medication metronidazole, too. Note: You can also find much more information about pinched mantle and what to do about it online by taking a look at Fatherree (2006b).

As far as what's in the scientific literature that can affect tridacnids, that's all I can find regarding microbes. However, it's important to note that there may be many, many more sorts of things from viruses, to bacteria, to worms that might affect tridacnids. Again, I haven't found anything other than what I've presented above, but you can take a look at numerous sources, such as Paillard et al. (2004), Bower (2001), Bower & McGladdery (2001), Hine & Thorne (2000) and Dungan et al. (1989), and see just how many known infectious diseases and parasites affect various other sorts of clams. Many clams that are aquacultured for food have been given far more attention than tridacnids have, and after seeing all of the things that researches have come up with that affect food clams, I can't help but think that tridacnids likely have far more tiny enemies than have been documented.

Lighting Problems

Corals are particularly simple as far as animals go, and they require relatively few calories to get through the day. On the other hand, tridacnids have a complete digestive system, gills, kidneys, a heart, blood, etc. and burn up much, much more energy than corals. So, many tridacnids require more light than many corals do. Each species of giant clam is different though, and some certainly need more light than others in order to thrive. For example, Tridacna crocea is found only in very shallow waters in the wild and needs more light than the other tridacnid species. In fact, I'm quite certain I've never seen one living more than about 10 feet down. Conversely, I've found numerous specimens of T. gigas and T. squamosa living at well more than twice that depth, and T. derasa can often be found living even deeper. Regardless, don't make the mistake of automatically thinking that if a given lighting system is bright enough to keep various types of corals alive and well that it's also automatically bright enough to keep various types of tridacnids alive and well. Maybe it's not.

Personal experience and the stories of others' have convinced me that there's a great deal of variability amongst clams of the same species when it comes to lighting needs, too. In other words, if a given lighting system is bright enough to keep one specimen of Tridacna crocea alive, that doesn't necessarily mean it's bright enough for all specimens of T. crocea. In any given batch of T. crocea, there will be some that grow faster than the others, some that get bigger than others, some that are more resistant to bleaching/disease than the others, some that are more brightly colored the others, and some that can thrive under less light than the others. Get the idea? It's simply due to genetic diversity within the species, and that's the reason that I generally make a conservative recommendation of placing any specimen of any species under intense metal halide lighting, a lot of high-output fluorescent bulbs, or something comparable like a good L.E.D. fixture.

With that said, it's time to say that I think the vast majority of mysterious clam deaths are simply due to insufficient lighting. Certainly not all cases, but most of them. The problem is that too many hobbyists do exactly what I warned against above. They have a lighting system that seems to be perfectly fine for keeping a number of corals, so they assume they can add in a tridacnid, too. Unfortunately, Tridacna crocea, the most light-demanding of the bunch, is also often the most attractive choice, and most often picked, at that. Then the clam slowly begins to starve.

Here you can see that there is no new shell material at all, and the margins have been overgrown by algae. This gaping T. crocea has been in poor health for some time now, likely due to insufficient lighting.

The bad part is that it can take several weeks or even a few months for a tridacnid to finally starve to death, and they'll typically look just fine until they have reached the point of no return and start gaping. This is why so many hobbyists tell the same story, that their corals are fine, but their clam looked great for some months, and then up and died for no apparent reason - mysteriously. In reality, the deceased may have been in the process of dying since the day it was put in the tank. Look at it this way, if a specimen is getting 95% of the light it needs, then it won't just croak overnight. Instead, it will very slowly waste away. Of course, if it's getting only 5% of what it needs, then yes, it may take only a few days before problems start.

This is more "mysterious", as the shell margin of this gaping T. crocea is very clean, indicating that it has been in good health for some time and then became seriously ill relatively quickly. Lighting was not an issue in this tank, and everything else seemed fine. Yet, the clam started gaping and later died for no apparent reason.

On many occasions I've talked to hobbyists that have lost a tridacnid, and a few times have seen their tank and the shell of the deceased, and one thing keeps coming up - a lack of growth. In so many cases, I learned that while corals and such were growing fine in the same tank, the clam extended its mantle and looked normal (no signs of pinched mantle, bleaching, etc.) but never grew at all. And in just about all of these cases, I also find that they have relatively low-output lighting for a reef aquarium.

I didn't mention it above, but be aware that cleaner shrimps and algae-eating hermits will not attack a healthy tridacnid. However, if they sense that one is very near death (or dead) they will oftentimes start scavenging on the remains.

The key to preventing such a death is to regularly look for new shell growth. Assuming water quality is where it should be and that other skeleton-building organisms are thriving, if a tridacnid is not adding on new material to the edge of its shell, there's a problem. While there are uncommon specimens that have a yellowish/orangish/pinkish shell margin, the overwhelming majority should have a clean white one. It should never look "dirty", greenish, brownish, etc., which is the result of a lack of shell growth and the encroachment of algae right up to the mantle. In fact, small to medium-sized clams of any species should have a clearly visible clean white band of new shell material all the way around the shell margin, as they typically have much higher growth rates than larger, older clams. So, if you don't see a clean white shell margin and a clean band of new shell material on a small to medium-sized specimen, the problem is very likely insufficient lighting, and it'll need to be moved up closer to the lights, taken out of the tank, or rescued with a new lighting system.

I first would like to thank the Advanced Aquarist's staff for all their hard work in creating a first class online magazine. What a benefit it is for us "regular folk" in this great hobby to have a place like this, that with just a few mouse clicks we can access so much valuable information. When Wade invited me to have my reef featured I felt honored yet a little hesitant. I was a little worried my aquarium may not be quite up to the standard people might expect but then thought it's not always about where you are right now but where and what you are striving to be. I hope that through my photos and remarks you will be able to feel the passion I have for this hobby and get a sense of the enjoyment I receive from it. I have always been fascinated with the ocean and diverse life forms we find there. It truly is another world and I love this hobby that allows us to keep a small part of it in our homes. I am grateful to be given this opportunity to share my little piece of the ocean with you.

History & Tank Profile

I ran freshwater aquariums for years, African cichlids mainly and like many people seldom had less that two tanks going at any given time. When I shut my last one down in the late 1980's due to a leak I decided at that time that when I eventually got back into the hobby I would switch to salt water. In October 2004 that dream became a realization when I had a tank custom built. I thought I would begin my salt water adventure with a FOWLR and maybe add in a few soft corals to sway back and forth in the flow. I had seen this kind of display at some fish stores and thought they looked pretty cool. Within about four months I found I was actually buying coral as often as fish and my tank slowly started to become a reef. By spring 2005 I was up to about 24 fish, an RBTA, several LPS with a few leathers and mushrooms as well as some Montipora caps and digitata. My original lighting was a 72" Power Compact fixture which I thought was pretty bright and assumed it was all I would ever need. However, by the summer 2005 I knew I wanted to upgrade to Metal Halides so I could add in some so called "harder to keep" sps coral such as acropora. In July 2005 I upgraded to a 72" fixture with 3x175 watt & 2x 96 watt PC actinics. In September 2005 I added a sump and Dec 05 upgraded my protein skimmer. I once again figured I was all set. Then in summer 06 I added in an RO/DI unit with an auto top-off going to the sump. I finally switched to R/O because I had a major hair algae outbreak that almost killed my reef. It got so bad that I did a complete tear-down in September 2006 and was rethinking whether or not to even stay in the hobby. I obviously kept going which is a decision I am pleased I made. It turns out that my skimmer was running at about 1/3 capacity for several months which sent my nitrates through the roof. I fixed the skimmer which worked fine for awhile. Right after the skimmer ordeal my main ballast went in my light fixture so I was again at a crossroads. It helped me realize my reef wasn't where I wanted it to be anyway, so in October 2006 I once again upgraded my lighting. I decided on a 72" fixture that houses five HQI bulbs, two 150 watt 20 K and three 250 watt 10 K, that would allow me to create a better sunrise and sunset effect with a higher intensity and then added in some moon lights for extra effect. I have since added a T5 fixture to supplement the lighting to help give that little extra pizazz I had been looking for. Now I was closer to the intensity I wanted but the water was getting too hot. I decided after loosing many sps colonies from the heat that I needed a chiller. After installing the chiller I still questioned why it had to keep running so often to keep things cool, I mean my light was hot but not that hot. Anyway, I did some checking and discovered I had a faulty heater that was staying on 24/7 and this had likely been my biggest problem all along. That said the chiller is still a definite necessity and really helps keep the water temperature stable. Around that same time I also changed out the powerheads to Tunze's with a multi-controller. The difference in the flow and random surge has made a huge difference in keeping my reef happy and growing.

In November 2006 I connected what had been my acrylic 40 gallon cichlid aquarium in-line to use as an ornamental Refugium & Softie tank. The refugium is made up of live rock, soft corals, and macro-algae. This tank has an "old school" sump in the rear where I also keep a "cheato chamber" running on a reverse photo period. I have since added in a 40 gallon frag propagation tank. This has increased my water capacity to approximately 250 gallons. This extra volume along with the increased nutrient exportation has made a huge difference in helping to stabilize the system as well as virtually eliminate nuisance algae growth in the display. Adding more volume to the system meant more water draining to the sump in case of a power failure. Since it will only hold the amount of water that drains from the main display I drilled the sump wall and added an emergency overflow going to a 10 gallon tank. Fortunately, I haven't needed it so far but I am sure the day will come and it helps give some peace of mind against flooding. As you can see the last two years, have been a "reefer's roller coaster ride." It seems whenever my reef starts to do well "Murphy's law" kicks in and something else happens. The summer of 2007 was to be no different. I discovered our dishwasher located in the kitchen, on the floor directly above where the tank is, had been leaking and dripping straight into the tank for an undetermined amount of time. The drain hose had sprung a leak and who knows what chemicals ended up in the tank between the soapy dish water and the basement ceiling tiles, etc. Needless to say I took immediate action. I changed and added extra carbon and did seven water changes in eight days of 15% each and managed to save the majority of livestock but the SPS took a big hit. Most of it lived although I did I loose several nice pieces. Unfortunately what did live either bleached or browned out, but for the most part over the last six months it has bounced back quite nicely. There are still a few pieces I am patiently waiting on to color back up but my hopes are high. Bad things seem to happen in waves, so of course while the dishwasher incident was occurring my skimmer had also quit working. I was without a skimmer for most of the summer and in late August 2007, I upgraded to a much bigger unit that could handle the load. I was very fortunate to not have a huge algae bloom and I give Polyp-labs a lot of credit for keeping my nitrates under control as I kept dosing with "reef-resh" during that time. The new skimmer has a 24 inch footprint and is 30" tall so I had to install it away from the main display as there was no room for it. I modified the skimmer to drain into a 5 gallon bucket both as a help for emptying skim mate because it's inconveniently located under the frag tank and as a safe guard against it overflowing. No good sps drama would be complete without having a few "red bug" battles so I of course have had run ins with them and learned the hard way that nothing goes into the system without being given a dip for such pests. I have been lucky so far and never had acropora eating flatworms. Anyway, things have been pretty stable since then so I am keeping my fingers crossed and keep "knocking on wood" that this present trend will continue.

Husbandry

In January 2007 I started running the Polyp-Labs "Reef-Fresh" program which helps keep the nitrate levels in check using bacterial strains, amino acids and other supplements. It is said to give results similar to Zeovit, basically encouraging a low nutrient environment. I have been pleased with the results over this past year or so.

I use Randy Holmes Farley's 2 part recipe for dosing Calcium & Alkalinity. My reef has a demand which requires almost 500 ML of each on a daily basis to keep the levels stable. Magnesium is added at approximately 500 ML per week as per Randy's recipe. Potasium is also dosed daily while other trace elements such as Iodine & Strontium are dosed biweekly.

Routine Maintenance:

Skimmer - empty & clean twice a week

Pre-Filter bags - change twice a week

Carbon - change out monthly (media bag runs through an Aquaclear filter in the refugium)

Water Changes - 10-15% monthly

Prune & frag corals - as needed

Lighting Schedule:

Main Display:

8:00 AM -1 watt moonlights on 10:30 AM - moonlight off

9:00 AM - T5's on 9:30 PM - T5's off

10:00AM - 150 watt 20k m/h on 10:30 PM - 150 20k's off

12:00 PM - 250 watt 10k m/h on 8:30 PM - 250 10k's off

10:45 PM - 1 watt moonlights on 12:00 AM - moonlights off

white led moon phase light runs automatically via sensor while main lights are out

NOTE: I try to time the photo period in a way in which I can spend more time on the reef while it's active. By starting the lights a little later in the day they are on for a longer time after I get home from work which gives me more time to tinker and enjoy.

Refugium/Softie Tank

40 watt light on reverse photo period in the rear sump "Cheato chamber"

8:00 AM -actinics on 11:00 PM - actinics off

9:00 AM - pc's on 10:00 PM - pc's off

Frag Tank (250 watt Geisman HQI pendent)

9:00 AM - on 9:00 PM - off

Feeding Schedule:

Feeding is provided on a daily basis, generally twice per day, and food is alternated to give their diet a variety of flakes, pellets, brine(super)shrimp, mysis shrimp, cyclopeze and "nori" seaweed. I also mix in some "Reef-roids" or similar product, on occasion to provide some extra food for the corals.

Livestock

Fish & Inverts

Main Display

1-scooter blenny

1-yellow tang

1-blue tang

1-naso tang

1-chevron tang

1-coral beauty angel

1-royal gramma

1-bi-colour blenny

1-yellow tail damsel

1-4 stripe damsel

3-green chromis

2-black & white ocileris clowns

1-blue devil damsel

2-watchman gobies

1-niger trigger

1-black brittle star

1- Nardoa novaecaledoniae star

1 - yellow coris wrasse

Foxface rabbit fish

1-Blood Red hawkfish

1-longnose hawkfish

1-red serpent star

Hermit crabs

2-conches

Snails (Too hard to put a number on)

1-Entacmaea quadricolor (Green bubble tip anemone)

5-hawaiian feather dusters

Refugium/Softie tank

1-flame angel

2-skunk cleaner shrimp

1-yellow clown goby

1-marine beta

1-purple fire fish

1-blue striped pipefish

2-orchid dottyback

1-pencil urchin

Frag prop tank

2-banggai cardinals

3-fairy wrasses

1-potters angel

1-sailfin tang

1-rabbitfish

1-watchman gobie

1-fire shrimp

1-sea cucumber

Clams

5-Tridacna crocea

1-Gigis

1-Tridacna maxima

Live Rock

Coral

I don't know all the proper names of many of the corals in my collection so I will only list those that I have identified through research and/or a lot of help from others in the hobby who are more knowledgeable than me. Identification can sometimes be tough when trying to compare an aquarium coral with a picture of one in the wild from a book, especially when you enter reticulate evolution into the equation. With some acropora, I find that I often know what species they aren't but can't always tell exactly which species they are, at least while they're alive. Anyway, I have tried to list the corals by the general taxonomic family first and then by genus and species.

A Few Comments I've heard:

In Michael Paletta's book "Ultimate Marine Aquariums" he asks his subjects about some of their favorite remarks people make when they see their reefs. I hope he won't mind me borrowing his idea as I thought it's a good one and I often get a kick out of people's reactions when they see my reef for the first time. Here are just a few first time comments:

Oh my gosh, I've never seen anything like this before.

Is that salt water? Is all that stuff alive? Are those plants? They're all corals? Even those? Are they real? How did you get them?

Do you bring these back when you go scuba diving?

I used to have goldfish but it wasn't like this.

I've been diving before and it wasn't nearly as colorful as this.

One reaction I find quite rewarding is when people simply stand there and say wow. (repeatedly)

But being of Christian faith, I think my all time favorite comment was when one individual out of the blue stated "I've always believed in evolution but after seeing this I think there must be a creator."

Acknowledgements

I would once again like to thank Advanced Aquarist's for their interest in featuring my reef and as previously mentioned it's an honor. I also want to thank all the people who have helped to educate me and given their support since I got started. I would also like to thank the suppliers that have put up with my bending their ear trying to learn from their knowledge. There are so many people I have learned from, too many to mention here but I again want to thank all those who have willingly shared their knowledge, time and friendship. Thanks also to Mike Paletta who was very gracious in giving his blessing when I asked to borrow his idea. I especially want to thank my wife Penny for her years of unquestioning support and always giving me plenty of room to run with my dreams.

Summary

My aquarium's look and especially my tastes have continuously evolved. This amazing hobby has taken me up and down and back and forth, through euphoric feelings of reward to great depths of frustration. It is said that experience is what you get when you were doing one thing and expected something else. All the "school of hard knocks" experiences along with my desire to learn and improve have brought me to where I am today and I wouldn't trade them for anything else. There are of course many things I would do differently if I had a "do-over" but overcoming challenges and hard lessons are often the best teachers. I still have much to learn and am never satisfied for very long with what I've achieved so more changes to my reef are imminent. But for now anyway, I have what I would call an "SPS dominated Mixed Reef." With my reef continually growing and corals so often crowding each other, I have found that regular pruning is necessary so starting a "frag business" became the next logical progression of the hobby for me. Having frags available creates an opportunity for me to meet lots of great people in the hobby, make a lot of cool trades and even get a few costs covered now and then. This hobby has had quite a profound effect on me and has even changed the way I scuba dive. I used to mainly look for the big things; dolphins, rays, turtles, sharks, eels, etc which I will always enjoy seeing, but since having my own reef I spend more of my dives looking at coral details and the small things many people miss such as Christmas tree worms, nudibranchs, flatworms, tunicates, etc. I enjoy it more than ever. I hope that my write up and pictures have provided a little something for everyone to enjoy and that my love for the hobby is apparent through my story. I wish you all good luck and happy reefing.

]]>No publisherGreg TimmsPomacanthus Publications, Inc.BulbsClamsEquipmentRO/DICoralGorgoniansSumpCalciumChillerCarbonpHFeatured AquariumGreg Timms2008-04-15T00:00:00ZPageFeature Article: Coral Coloration, Part 9: Tridacna and Other Photosynthetic Clam Coloration, With Observations on Possible Functionshttp://www.advancedaquarist.com/2008/1/aafeature3
This month, we will continue our observations of marine invertebrate coloration with a slightly different subject - that of the impressive appearance of photosynthetic clams.Click through to see the images.

With full realization that I'll get email stating that 'clams are not corals', I can not be content to leave it at that. So, I will make an even bolder statement - Tridacna clams' tissues (along with certain other genera) are colorless and contain no spectacular pigments. You are paying good money for an optical illusion. But what an illusion!

This month, we will continue our observations of marine invertebrate coloration with a slightly different subject - that of the impressive appearance of photosynthetic clams (mostly Tridacna and Hippopus species, but also including Fragum, and Corculum specimens). Strangely enough, and contrary to information in many hobbyist references, these clams do not contain colorful pigments. The 'metallic' iridescent colors we often see are caused by light reflected from tiny internal structures. Also involved are refraction, light interference and possibly diffraction. To understand why these colors are apparent necessitates a review of a few optical physics terms.

Definitions and Examples

Coral coloration (due to reflection and fluorescence) is relatively simple when compared to the science involved with clam coloration. Take a deep breath, and we'll get started.

Diffraction: Bending of light waves around an object. The colorful surfaces of CDs and DVDs are good examples of diffraction.

Hue: One of three attributes of color (along with chroma and lightness). This attribute is described with names such as 'red', 'yellow', etc.

Interference: A characteristic of light waves under certain circumstances to reinforce or cancel hue. Reinforcement is called 'constructive' interference while cancellation is called 'destructive' interference. Interference is caused by light waves traveling at different speeds and staying in or out of phase. If the light beams are of the same orientation after reflection/refraction, no color will be apparent. However, certain colors will be amplified if beams are out of phase (within a very small range).

An example of interference can be seen when two pebbles are dropped into a tub of water. Some waves will combine and become larger while others' energies meet and 'cancel out.' Basically, the same thing can happen with light waves during constructive or destructive interference.

The colors of soap bubbles or oil on water (and Tridacna iridescence) are due to constructive and destructive interference (See Figure 1).

Figure 1. A common example of interference. These bubbles do not, nor do Tridacna clams, contain pigments that make them iridescent. Light reflected from the inside and outside surfaces of the bubble recombine and, if out of phase, cause constructive interference and different hues. If in phase, no color is apparent due to destructive interference.

Note that clam iridophores are made of different proteins than many other animals' iridophores. For instance, cephalopod (squid, octopus, etc.) iridophores are based on a different material (guanine, which is why their iridophores are sometimes called guanophores. If that sounds a little odd - it is. Guanine was originally isolated from guano, or bird poop. This little known fact can make you the life of the next black tie cocktail party you attend…and make you wonder about the motivation of some scientists!).

Iridescence: An optical phenomenon in which hue ('color') changes with the viewing angle.

Reflection: The 'return' or 'bouncing back' of light waves, sometimes (but not always) without alteration of the light and incident angle.

Refraction: Deviation or 'bending' of light waves as they pass from one medium to another of different optical density. The amount of 'bending' caused by a material is called its refractive index.

Mirages are due to refraction caused by layers of cool and warm air.

Schemochromes or 'Structural Colors': Those colors caused by presence of tiny light-reflecting structures and optical physics such as refraction, interference and others. Schemochromes are the opposite of biochromes (which contain true colored pigments). Therefore, schemochromes are not actually pigments but only an optical illusion caused by structural properties (and widely seen in many bird feathers, reptile and fish scales and tissues, insects and marine invertebrates).

To stitch this information together - the 'metallic', iridescent colors displayed by Tridacna and other taxa are not true pigments (biochromes) - they are schemochromes. Schemochromes are due to physical structures within tissues. In the case of colorful clams, these structures are called iridophores. Iridophores contain uniform, protein-rich cells called iridosomal platelets. When light strikes the iridosomal platelets, it is reflected but not without modification. The color reflected is dependent upon the refractive index of the protein, its orientation, number of platelets in the stack, angle of illumination and other factors. Thus, light falling upon the platelets is refracted (due to different optical densities). Construction and destructive interference now come into play. Again, depending upon the refractive index and possibly the orientation of the proteins, interference can reinforce certain colors, or cancel them. These refracted/reflected light waves can be
very dramatic in appearance if the background is dark.

If the exact refractive index is known (and, to my knowledge, it is not for Tridacna and others), then the apparent color can be predicted. Constructive interference (assuming a refractive index of 1.42) would occur at wavelengths in the range of ultraviolet (355nm) through blue (468nm; Griffiths et al., 1992)*. In other words, the structural colors reflect ultraviolet light (which we cannot see) and those visible wavelengths of violet and blue (which is the color of many clams' mantles). Different refractive indices could lend any number of visible colors.

* Note: These researchers believed preparation of mantle samples may have caused some shrinkage, thus throwing a small monkey wrench into the works. When the calculation is 'corrected' for this potential error, the constructive interference range is extended into the green portion of the spectrum (and, as we know, violet, blue and greens are quite visible in mantles' reflected light).

Discussion

If we have in mind a concept of what causes clam iridescence, then the next logical question is 'why?'

The most popular theory seems to be one of photoprotection, where potentially harmful ultraviolet (UV) radiation and Photosynthetically Active Radiation (PAR, especially in the violet/blue/green portions of the spectrum) are simply reflected away from the animal and its symbiotic algae.

A simple test, though certainly not conclusive, would be to compare clam coloration to depth. Theoretically, clams reflecting blue and green light would be found in shallow depths. See Table 1.

Table 1. Common clam coloration and depths. Casual observation suggests blue and green colors are common in clams from shallow water, while yellows and browns are often seen in specimens from deeper water. Is it really so?

Species

Common Depth

Common Colors

Tridacna crocea

to ~6m

Blue, Green

Tridacna maxima

Common to 7m, but to ~20m

Blue, Green, Violet

Tridacna squamosa

To 15-20m

Golden Brown

Tridacna trevoroa

20-33m

Brownish-Gray

Tridacna gigas

20m

Green-Brown

Tridacna derasa

4-10m, but to 25m

Golden Brown

Hippopus hippopus

to ~6m

Dull Greenish Brown

Before continuing, it should be noted that any attempt to associate fashion (coloration, in this case) with function is notoriously difficult. However, with that said, generally we see blue and green coloration associated with clams often found in shallow depths, with yellow-browns at deeper depths. However, there are major exceptions to this apparent trend where clams of a single species at the same depth display radically different coloration (see Fatherree, 2006 for some striking examples). Hippopus specimens also buck the trend.

So, other factors should be considered, such as genetic variability among specimens and possible effects of environmental factors. 'Types' (clades) of zooxanthellae found in photosynthetic clams should be studied when examining maximal depth ranges of clams.

Burton (1997) used a laboratory procedure called electrophoresis in an attempt to link mantle 'coloration' and genetic variations. No clear relationship was established (although some interesting anomalies were observed in some of his colorful T. gigas specimens). This researcher believed unspecified environmental conditions (perhaps in conjunction with genetic predisposition) could cause 'expression of color'.

The most common environmental factor mentioned in hobby literature is that of light intensity or spectral quality. Alo (2005), in tests involving almost 400 T. maxima specimens distributed in 12 greenhouse systems and using different lighting setups in each system ('full greenhouse' light - peak PAR of 1,300-1,400mmol×m²×sec; 'shaded greenhouse' light - peak PAR of 700-1,000 mmol×m²×sec; and 10,000K metal halide light - maximum PAR of 1,450 mmol×m×sec, decreasing to 280 mmol×m²×sec (!) after 13 weeks), found onlyoneT. maxima to shift coloration (from green to yellow) during the experiment's progress (this specimen was held in a 'shaded greenhouse' tank). However, during the clams' light acclimation period (an initial 5-hour photoperiod increased by 30 minutes daily until a 12-hour photoperiod was obtained) fourteen clams changed from green to gold, and two switched from blue to gold.

Of interest to many hobbyists is one of Alo's observations - those clams maintained under the 10,000K metal halide lamps never expanded their mantles as fully as those exposed to natural sunlight of any intensity. His work suggests spectral quality was in play, and he attributes statistically significant high clam mortality to the UV-A spike at 365nm in the metal halide's spectrum (which is an interesting observation, since other researchers have suggested refractive/reflective qualities produced by iridophores protect mantle tissues/zooxanthellae from UV-A radiation. Since the metal halide lamps were suspended 20 cm (8 inches) above the water surface, is it possible that infrared radiation - heat - generated by the lamps was transferred to the clams resulting in stress?). For those wondering, Alo keep careful records of nutrients within his systems.

This researcher also includes some interesting work determining reflectance of clams' mantles using an Ocean Optics spectrometer and its software (See Figures 3, 4 and 5).

Figure 3. Reflectance of a single T. maxima specimen before and after its transition from 'green' to 'yellow'. (The 'R' legend on the y-axis stands for 'reflectance'.)

Figure 4. Reflectance of a 'light blue' T. maxima. Note the unusual and very strong reflectance at ~440nm - ~20% of the light falling upon the mantle is reflected. There is a muted spectral signature of zooxanthellae seen at 575nm and 650nm.

Figure 5. Reflectance of a 'dark blue' T. maxima. Compare this weak reflectance to that of the 'light blue' clam in Figure 4. Also interesting is the distinct 'crown' reflection at ~575nm, 600nm and 650nm- the typical spectral signature of zooxanthellae. Why do reflectances shown in Figures 3 and 4 lack this pronounced feature?

And… A Final Clue

If Tridacna clams' coloration plays a part in preventing zooxanthellae from getting too much light, we would see this as lack of photoinhibition in photosynthesis (or specifically, a linear increase of electron flow as light intensity increases - this determined by a PAM fluorometer).

And this is exactly what we see (as shown in Figure 6). However, this is not proof that the mantle coloration is responsible - it could be due to self-shading of zooxanthellae within the relatively thick mantle, or some other factor.

This experiment was conducted while using an Iwasaki 400-watt 'daylight' metal halide as the illumination source. No photosaturation (much less dynamic photoinhibition) was noted at PAR values approaching 600 µmol·m²·sec, or ~30,000 lux. This does not mean the clam requires this amount of light; merely that it can tolerate it. T. maxima specimens can do just fine when maintained under much less light (200-300 µmol·m²·sec, or 10,000-15,000 lux, is generally sufficient).

Figure 6. Rate of photosynthesis (Electron Transport Rate, or ETR) of a Tridacnamaxima clam under an artificial light source.

Zooxanthellae Clades Found in Giant Clams

As we near the closing of our discussion, we should examine the 'types' of zooxanthellae known to infect Tridacna clams. Reasons for including this information are two-fold. First, it establishes that clams of the same species can contain different zooxanthellae 'types' (clades). It also suggests that animals in the listings could possibly have the same light requirements.

As to the real question - Is there a genetic link between a particular clam recognizing a specific symbiont clade and a need for photoprotection via optical manipulations?

Clam Coloration - Is It Camouflage?

Reflection of ultraviolet radiation could serve as a photoprotective measure to both host and symbiont, but is a poor idea for camouflage since many fishes can see well into the ultraviolet radiation range. Of course, the same applies to visible radiation. It would seem that clam mantle coloration is just the opposite of the best camouflage strategy - that of invisibility, such as offered by transparency, where background light is transmitted through tissues. Further, the apparent self-protection reaction made possible by clams' photoreceptors (primitive 'eyes') to shadows is well known - the sudden closing of the valves, where water is forced out of internal cavities (usually enough to scare away predator fishes, such as Thalassoma wrasse spp. This, naturally, does not exclude camouflage's potential of predator avoidance, if you will. However, some researchers believe mantle coloration acting as camouflage to be a remote possibility).

There is also the possibility that physical qualities of the mantle could enhance photosynthesis. However, there is very little evidence supporting this hypothesis and it will not be discussed here.

I present this information for those truly interested in pursuit of answers. Unfortunately, I can no longer work on this since NELHA donated their Tridacna clams to the Waikiki Aquarium.

It should be apparent that we have a fairly good understanding of how clams' mantles are colorful, but a very poor one of why they appear this way.

This is an excellent project for a dedicated hobbyist to undertake. Quality spectrometers are becoming increasing affordable as diffraction gratings find their way into different applications, and a fair number of instruments are now in hobbyists' hands. Those hobbyists willing to expend their time and money could be rewarded with unlocking mysteries of clam coloration - how they do it, why they do it - and perhaps turning those less-than-desirable specimens into 'killer clams'.

Yoshihisa, K., undated. Organization and development of reflecting platelets in iridophores of the giant clam Tridacna crocea Lamarck: Developmental biology.

Zoo. Sci., 7(1):63-72.

]]>No publisherDana RiddlePomacanthus Publications, Inc.ClamsCoralDana RiddleColorationFeature Article2008-01-15T00:00:00ZPageHot Tips: Clam Selection Tipshttp://www.advancedaquarist.com/2006/5/tips
This month, our readers give advice on selecting that special clam at the LFS.Click through to see the images.

Clam Selection Tips:

One of the most important things is the reaction test:

Place your hand between the clam and the light. If the clam reacts to the sudden shade by closing up, it's at least reasonably healthy. If the clam responds very slowly or not at all, leave it. Clams have a type of "spring" that forces them open; closing is an active mechanism and is the sign of a healthy clam.

Also, be on the lookout for any bleached or torn sections of the mantle, as well as making sure the mantle extends beyond the shell. However, note that the mantle of Hippopus species does not extend much past the shell. It's also worth noting that T. gigas naturally has uniform clearer spots in the mantle; these are totally normal.

Finally, consider size when purchasing a clam. Very large clams can sometimes have trouble acclimating; on the other hand, very small clams are obligate filter-feeders until they get larger. The safest bet is a good mid-sized clam. You also want to consider adult size: T. gigas, T. deresa, and T. squamosa all get very large and grow quickly. It would be irresponsible to house them in an environment which they will quickly outgrow.

Good luck, and have fun!

Submitted by T. Dornhoffer

Look at the mouth (incurrent siphon). If it is very wide and gaping, I would not recommend purchasing this clam.

Submitted by Len

Inspect the clam for parisites prior to adding it to your reef. Snails can hide under the mantle as well as other hitch hikers that you might not want. Also check the shells for holes this is also a sign of parisites.

Submitted by Angry John

Make sure the mantle is rich and deep in its color with out any white spots that break the pattern. The flushing of zooanthellae is a deffinite sign of a clam on its way out.

Submitted by Hedonic

There are still occasions where even though all of the positive signs mentioned above are shown, other possible red flags may go unnoticed. Sometimes the tank inhabitants can also offer premonitions of a clam that might otherwise appear completely healthy.

A shrimp clinging patiently on the shell. Hermits or bristleworms congregated at the base of the shell near the byssal opening. These are telling signs of impending internal deterioration that aren't indicative by the clams appearance.

Submitted by Unarce

]]>No publisherAdvanced Aquarist's ReadersPomacanthus Publications, Inc.AcclimationBeginnerClamsHot TipsNoviceStress2006-05-15T00:00:00ZPageFeatured Aquarium: The Aquarium of Richard Kurzydlohttp://www.advancedaquarist.com/2006/4/aquarium
Richard shares his 55 gallon reef aquarium with us this month.Click through to see the images.

Note: Additional photos can be found in this article's photo
album.

First off it's a great honor to
be chosen for the Featured Aquarium. Who would have ever known
that this hobby would have taken me to the levels that I have
attained within saltwater aquariums. I've been involved with the
aquarium keeping scene since I was just a kid of 14 yrs old. My
mother brought my first tank home on day - a 20 gallon high. I was
hooked from that point on. As for saltwater, it's been a short 3
years that I have been knee deep in reef keeping! What can I say?
It's an addiction to which I have not yet seen a cure.

The tank

It all started, January 2003, when I received a call from a
friend who said he was moving to New York and who asked if I
would like to take over his saltwater aquarium? Free of charge.
How could I say no? Two and a half years later, I have two tanks
going, a 15 g and a 55 g. This article details my well populated
55g reef display.

Initially, the tank was setup in August 2003 to accommodate
about 80 pounds of live rock a friend had that needed a place to
be housed as he repaired his leaky tank. The tank was set up with
a 4-5 inch DSB and live rock. It sat empty until January 2004
when my friend decided it was time to return his live rock. In
the end, I was able to keep one rock from his collection. Since I
had my first SPS given to me, a chip-sized piece of
Pavona, which I had glued to the center piece, I was
able to keep that one rock. Granted it was his largest piece of
around 18 pounds… such a great friend. That center rock
still sits in its original position with a softball sized colony
of the same Pavona growing on it. After that I needed to
fill the tank with live rock once again. I was very fond of the
Fiji rock and the Tonga branch rock so I have the complete right
side of the tank filled with about 40 pounds of Tonga and the
left side with approximately 30 pounds of Fiji. As the picture
indicates now, the rock work has stayed in place for 2 years now
- if it works, leave it alone.

I feed the tank with a mixture that was made with about 6
frozen and 3 flakes varieties combined. I also use Vita-Chem and
Phytoplankton for the corals. Tank is fed once every three days.
I found with less feeding I don't get ANY undesirable algae
outbreaks and the tank stays a lot healthier.

Take your time, read books, visit the web and absorb as much
as you can. Don't be afraid to try something new and keep up on
your husbandry. (Yes, that means water changes for those that
don't do them!) I feel with this regiment you will have a
successful tank for many years to come. Furthermore, this hobby
requires patience and money. Visiting places like
Reefs.Org, I have been able
to learn and obtain great knowledge from fellow aquarists that
have been helpful in responding to questions, gripes, and
assisted with the background know-how of our awesome hobby.

I appreciate everyone taking the time to read about my tank
setup and its inhabitants. If you have any questions or comments,
positive or negative, I'd love to hear from you.
Racenrich@wideopenwest.com

In early 2003 it occurred to me that my old 80 gallon (330l)
freshwater tank might also do for a reef tank. When I studied the
various ways and approaches of reefing, I got biased towards
reducing technology in favour of an utmost "natural
management" of nature.

Thus I decided not to use a skimmer and also do without any
kind of conventional (mechanical) filtration. Since there were no
drillings in the groundplate I also dropped a sump below the
tank. Into the right corner at the backside I glued in an
overflow consisting of a separate compartment from where the
water is immediately transmitted back into the tank.

Among the different natural filtration systems the
"Jaubert System" pleased me because of its simplicity
and its advantages with respect to micro life. In July 2003 I
covered one third of the ground at the backside with a 5 inch
high Jaubert ground which consists of a 1 inch plenum constructed
of eggcrate and covered with a common fibreglass window screen. A
four-inch sandbed (grain size 3-4mm) was placed on this
construction. A bent acrylic strip served as a barrier to the
foreground. I used silicon glue to secure this barrier.

For the lighting I confined myself to 4x54 Watt ATI T5 bulbs
with good parabolic reflectors, and this turned out - contrary to
common opinion- to be enough light for good SPS growth.

In the spring of 2004 the rich life and excellent coral growth
motivated me to make some improvements:

Instead of manually adding Kh and Ca liquids into the tank
every day, I installed a Grotech TEC III dosing station which
now adds the solutions at set intervals (currently eight times
per day).

To enhance coral colors, I changed the light spectrum more
to the blue by using two ATI blue plus and two ATI aquablue
special.

To raise the pH and oxygen at night, which could become
problematic in my unskimmed system, I decided to connect a
second, smaller tank (35 gallon) which is kept on a reverse
illumination cycle (light at night, dark during the day). The
extra tank, or refugium, consists of a frag and algae chamber
on one side and a sedimentation chamber on the other.

From the beginning there was a very low concentration of
nutrients (NO3=0mg/l; PO4= 0-0,024mg/l measured with Merck) due
to the combined efficiency of the Jaubert System, the fair amount
of corals, and the regular harvesting of (blue appearing) brown
algae
(
Dictyota sp.). As it seems to me, to the low
concentration of nutrients is an important ingredient for the
rich variety of coral colours in the tank.

Hopefully this has provided you a short insight on how my tank
functions.

Equipment

Tunze Stream 6010 with multicontroller

Aquabee 1000 (circulation refugium)

Tetra 150W heater

Grotech TEC III dosing station

Zajac Pegel Plus (automatic evaporation refill)

Lighting

4x54W T5 (maintank)

2x24W T5 (refugium)

moonlight

Maintenaince

Daily: dosing of trace elements (AquaConnect energy
elements 1-3)

Daily: feeding various dry and frozen food

Every 10 days: measurements of Ca and KH (KH 6-8, Ca
400-420)

Every 5 weeks: water exchange (about 10 gallons)

Mg, PO4, Nitrate is measured

Once a month: top the 2.5 gallon KH and Ca canisters (with
a German variation of the "Two-part additive system"
called the "Balling Methode")

This article will feature a glimpse into some of the
gadgets used in the marine aquarium hobby. The author
frequently receives emails asking for input on products,
however this article is intended to introduce readers to the
vast world of aquarium products. Several of the items
mentioned here have not been used by the author and should not
be viewed as endorsements.

Ahh, the joy of handing out fish goodies to bright eyed young hobbyists.

Inspired
by a Fish Geek Holiday party last year, the author awoke one morning to
find a digital thermometer wrapped up nicely by a loving wife.

It's that time of year again. One of my favorite times of
the year is when reef people around the world celebrate a
Holiday Season. For me, this means the pleasure of attending
another Reef Geek Holiday Party. These events are typically
designed for a bunch of "Fish Geeks" to get together and enjoy
the company of other overly obsessed hobbyists. Another
enjoyable part of these events are seeing new aquarium
products, with freebies and donations as well.

For some of you in large hobbyist clubs and public aquaria
the fun and games of Reef Parties is all too familiar. For
everyone else, here is a look into what you may be seeing in
stores this Holiday Season.

Nothing beats hanging around with fish friends.

During
a Fish Geek Holiday party a power point presentation is shown
describing holiday gift ideas and descriptions of donated products.

Shown here are examples of items donated and given away at a Fish Geek Holiday Party.

Low Budget Items

Can you believe all the little things you can buy
in this hobby? I believe it to be only second to the scuba
diving hobby. From digital thermometers to hand held
magnifying glasses to fish foods to hermit crabs, low budget
items are everywhere. Some hobbyists have even been known to
make Christmas Stockings that are stuffed with all aquarium
related items.

Not
sure what will be in your stocking this year? Try wishing for one of
these stockings stuffed with fish food samples and aquarium additives.

Some Fish Geeks have everything for their tanks, but a little bit of fish room décor is always an option.

Tired
of trying to read that little algae covered glass thermometer which is
always turned around backward? Try using a small out of site digital
thermometer.

Some items need to be replaced continuously. For that reason some activated carbon is always a good gift.

For
our readers in the Southern Hemisphere we should mention that the
upcoming summer season is upon you. Now may be a good time to add a fan
or two above your tank.

Cheap
float valves can be installed on most aquariums. They offer relief from
manually adding water and checking water levels in an aquarium.

If
you are tired of seeing your spouses aquarium covered with that dirty
film on the glass/acrylic then this is for you. Magnet cleaners are
cheap and easy to use for removing algae from the front of an aquarium.

Not
often used in reef aquariums, but still intriguing items, mood lights
offer a different perspective and look to the aquarium.

Moon
light systems are designed to give your aquarium that nighttime glow.
Often cheap to buy and commonly made at home these lights are
increasingly popular.

Time to clean the tank? Hate that coralline algae on the front? Try using a scraping tool like those shown here.

Some test kits (Alkalinity, Calcium, etc) should be owned by all aquarists, but there are numerous other kits available as well.

One
of the best gifts you can give is something that gives back to your
local aquarium club. Some of these gifts generate tremendous
advertising for aquarium clubs.

By
purchasing an aquarium club gift, like the super stein shown here, you
are not only buying a gift but are also financially supporting your
local club.

Middle Budget Items

Well these are the gifts for that special friend
you might have. Say someone like your local aquarium club
president! If that doesn't work, you may want to consider
treating yourself this holiday season with one of these
additions to your aquarium.

The perfect gift. Books contain an abundance of information and are perfect reference tools for the every day hobbyist.

Typically
livestock is not the best choice of a party gift. On the other hand who
can resist adding a new addition to their ecosystem.

Dosing
pumps are used by hobbyists usually to control the input of buffering
solutions. Before purchasing or using such a device make sure you
understand how it works and know what you are doing.

If
you are going to be home for the holidays then let this be a time where
you take care of some aquarium projects. One example is to remove all
those unsightly (and unsafe) powerstrips and cords you have, and to rig
up your own aquarium power box.

Externally mounted powerheads are new on the market. Look for their popularity to take off in the near future.

Even
small aquariums can benefit by adding a refugium. If don’t have a
refugium on your aquarium you may want to consider adding one. Shown
here is a simple refugium made to hang on the back of the aquarium.

High Budget Items-

High budget items are not usually the best gifts
to give, but are certainly the best gifts to receive. Honestly
purchasing a High Budget Item is often unnecessary as most of
these items are chosen by hobbyists for specific purposes. I
would like to review some of these products because some of you
may be fortunate enough to convince a significant other that
you really need one of these items. If that is the case, I
certainly recommend that you pick out the exact style and
manufacture that you are looking for.

A Calcium Reactor set-up is a large purchase that requires proper planning.

Automatic controlling systems are becoming more popular as the hobby expands.

Kalkwasser Reactors are great additions to an aquarium, and also make great Do It Yourself projects.

For the reefer who already has everything, a mesoscope can offer new perspective on aquarium inhabitants (photo of author)

Given
away during an aquarium club holiday party, this Oceans Motions unit
creates changing water currents (unit shown on the back of the aquarium
directing water through pvc plastic piping).

Running
Ozone in a reef aquarium has numerous benefits. However, this is
certainly a compound in need of proper care and understanding. A gift
best left for experienced hobbyists.

Water purification systems are recommend by most hobbyists as a great addition to reef aquarium set up.

If
you drew Dana Riddle’s name out of the holiday season hat then a trip
to the local science store may be a prudent move. In fact many
hobbyists are playing with scientific tools on a daily basis as they
delve into this hobby.

If
you don’t already have a protein skimmer on your aquarium, then this is
the perfect time to look for one. Skimmers are considered to be one of
the most effective waste removal devices used in the hobby today.

Shown
here is a Wave2K box that generates a repeating surge of water through
out the aquarium. You can click the links to see videos of the item in
motion.

The Important Part

Let us not forget the important things during the
Holidays. The best part of a Reef Geek Party is the
camaraderie and enjoyment of seeing friends. I hope all of you
will enjoy the Holidays with your fishy friends as much as I
know I will.

If you are looking to buy a gift for your favorite club president, this skimmer may be a good choice.

Embarrassingly revealed the fish party cookies are a favorite of this author.

On
a final note the author would like to say “Happy Holidays and cheers”
to all of you. I hope you have as much fun with your fish friends this
season as I know I will.

Author Information

Adam Blundell M.S. works in Marine Ecology, and in Pathology
for the University of Utah. He is also Director of The Aquatic
& Terrestrial Research Team, a group which utilizes
research projects to bring together hobbyists and scientists.
His vision is to see this type of collaboration lead to further
advancements in aquarium husbandry. While not in the lab he is
the president of one of the Nation's largest hobbyist clubs,
the Wasatch Marine Aquarium Society
(www.utahreefs.com). Adam has earned a BS
in Marine Biology and an MS in the Natural Resource and
Health fields. Adam can be found at
adamblundell@hotmail.com.